Basic concepts in biology. Basic biological terms (Dictionary)
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Terms
Etymology
Definition
Autotrophs
From Greek autos - self, trophe - food
Organisms capable of independently synthesizing organic substances from inorganic ones using solar energy and the energy of chemical transformations. These are green plants and some bacteria.
Anaerobic bacteria
From Greek an - negative particle, aer - air, bios - life; bacterion-rod
Organisms that can live and develop in the absence of free oxygen in the environment.
Antennas
Short antennae in crustaceans
Antennas
Crustaceans have long antennae.
Arterial blood
Blood saturated with oxygen.
Archaebacteria
From Greek archios - ancient, bacterion - rod
The oldest living prokaryotes appeared 3 billion years ago.
Aerobic organisms
From Greek aer - air, bios - life
Organisms that can live and develop only in the presence of free oxygen in the environment (all plants, most protozoa and multicellular animals, almost all fungi).
Bacteriophage
From Greek bacterion - rod, phagos - eater
A virus that infects bacteria.
bacilli
From lat. bacilli rod
Elongated bacteria.
Biosphere
From Greek bios - life, sphere - ball
The shell of the Earth inhabited by living organisms.
Biocenosis
From Greek bios - life, koinos - general
A collection of animals, plants, fungi and microorganisms that jointly inhabit an area of land or body of water.
Binary nomenclature
From lat. binarius – double, consisting of two parts; nomenclature - list of names
Designation of species in two words: the first is the name of the genus, the second is the specific epithet.
Side line
The organ that senses water movement, characteristic of fish, is formed by sensitive cells grouped on the lateral surfaces of the body.
Botany
From Greek botane - grass
Plant Science.
Frond
From the Greek bayon - palm branch
fern leaf
Deoxygenated blood
Blood that gives oxygen to the cells of the body.
Vibrios
From franc. vibrio - hesitating, trembling
Arched bacteria
(the causative agent of cholera).
View
From lat. spices - standard, unit of measurement
Basic unit of classification. A set of individuals that have a similar structure, lifestyle, are capable of interbreeding with the appearance of fertile offspring and inhabit a certain territory.
Virus
From lat. virus-venom
Non-cellular life form.
Virology
From the Latin virus - poison; Greek logos - doctrine
The scientific discipline that studies viruses.
Water vascular system
Characteristic of echinoderms. It is represented by a ring canal surrounding the esophagus and five radial canals extending from it into rays. Participates in locomotion, respiration and excretion.
Brood
Birds whose chicks, soon after hatching from the egg, are able to follow their mother and independently peck food.
Gametophyte
From Greek gamete - wife, gametes - husband; phyto-plant
A plant that produces gametes.
Hemolymph
From Greek gem - blood, lat. lymph - pure water
A colorless or greenish liquid that circulates in the vessels or intercellular cavities of many invertebrates (arthropods, mollusks, etc.) that have an open circulatory system.
Genome
From Greek genos- origin
The set of genes in the haploid set of chromosomes of a given organism (the human gamete genome is represented by 23 chromosomes).
Hermaphroditism
From the names of the Greek the gods Hermes and Aphrodite; translated means - a mythical bisexual creature.
The presence of male and female organs in the same individual.
Heterotrophs
From Greek heteros - other, trophe - food
Organisms that use only ready-made organic substances for nutrition.
Hydromedusa
From Greek hidor - water, moisture;
Free-swimming sexual specimens of the hydroid class.
Hyphae
From Greek hife - fabric, cobweb
Microscopic branching threads that form the vegetative body of the fungus - the thallus.
Mycelium
The vegetative body of a fungus (thallus), consisting of thin branching filaments - hyphae. Serves to absorb nutrients from the substrate.
Caterpillar
A worm-like butterfly larva with a segmented body and no more than five pairs of legs.
Double fertilization
A type of sexual process characteristic only of flowering plants. The point is that when a seed is formed, not only the egg is fertilized, but also the central nucleus of the embryo sac.
Bilateral symmetry
Symmetry, in which organs are located on either side of an assumed plane dividing the body lengthwise into two halves.
Diaphragm
From Greek diaphragm - partition
A muscular septum dividing the body cavity into thoracic and abdominal sections.
Diplococcus
From Greek di- two, coco- grain
Bacteria consisting of pairwise close cocci (two cells in one capsule).
Natural selection
The main driving factor in the evolution of organisms. The result of the struggle for existence is expressed in the preferential survival and leaving of offspring by the most adapted individuals of each species of organisms and the death of the less adapted.
Zarostok
The sexual generation (gametophyte) in higher spore plants (moss mosses, horsetails, pteridophytes). It develops from a spore and forms male and female reproductive organs.
Zoology
From Greek zoon - animal, logos - teaching
The science of animals, studying the diversity of the animal world, the structure and vital activity of animals, distribution, connection with the environment, patterns of individual and historical development.
Immunodeficiency
From lat. Immunitas - liberation, deficiency - lacking
The body's inability to resist any infections.
Instinct
From lat. instinctus - urge
Complex, hereditarily determined behavior characteristic of individuals of a given species under certain conditions.
Artificial selection
The choice by a person of the most economically valuable individuals of animals, plants, microorganisms of a given species, breed, variety, strain to obtain from them offspring with desirable properties.
Carotenoids
From lat. karota - carrots; Greek eidos - form, appearance
Red, yellow, and orange pigments found in plant and some animal tissues.
Cambium
From Greek cambium - exchange
Educational tissue located between wood and bast and causing their growth in thickness.
Keel
Most birds have a high ridge on the sternum.
Classification
From lat. classis - rank, class, fauere - to do
Distribution of the entire set of living organisms according to a certain system of subordinate groups - taxa (classes, families, genera, species, etc.)
Cloaca
Lat. cloaca
The expanded portion of the hindgut into which the digestive, excretory, and reproductive systems open.
Cocci
From Greek coconut grain
Bacteria having a spherical shape.
Cocoon
Fran. cocoon
A protective formation that protects eggs, embryos or pupae.
The colony
From lat. colony-settlement
A group of cohabiting individuals of one or more species that are capable of living independently.
Competition
From lat. konkurrere - collide, run together
Relationships between organisms of the same species or different species competing for the same environmental resources when the latter are scarce.
Cuticle in plants
From lat. cuticle - skin
A layer of fatty substance that covers the surface of the above-ground organs of many plants with a continuous film. Plays a protective role.
Cuticle in animals
From lat. cuticle
A dense noncellular formation on the surface of epithelial tissue cells.
Shedding
Periodic change of outer integuments and their various formations (scales, wool, feathers, etc.).
pseudopods
Temporary cytoplasmic projections in unicellular organisms and some cells of multicellular animals (eg, coelenterates).
Radiation symmetry
Symmetry, in which identical organs are located along rays diverging from the center (sponges, coelenterates).
Mantle
From Greek mantle - cloak
Two folds hanging down the sides of the mollusks' body.
Uterus
A hollow muscular organ within which the baby develops.
Megaspore
From Greek mega - large, spore-seed, sowing
Large female spores in ferns.
Mesoglea
From Greek mesos - average, intermediate; gleios - sticky
A structureless gelatinous substance lying between the ecto- and endoderm of sponges and coelenterates. Highly saturated with water (up to 98%).
Mesoderm
from Greek mesos-medium, derma-skin
The median embryo sac in multicellular animals, including humans.
Mycology
From Greek mycos - mushroom, logos - teaching, science
The science of mushrooms.
Mycorrhiza
From Greek mikos - mushroom, rhiza - root
Symbiosis of fungal mycelium and the roots of a higher plant.
Microbiology
From Greek micros - small, bios - life, logos - science
Biological discipline that studies microorganisms.
Microspore
From Greek micro- small, spore- seed, sowing
Small male spores in ferns.
Mixotrophs
From lat. mixio-mixing
Organisms with a mixed type of nutrition: they are capable of photosynthesis, but also feed on organic matter, eating bacteria and other protozoa.
Spawning
The spawning of reproductive products by fish - mature eggs and milt - followed by fertilization.
Social insects
A number of groups of insects that form permanent (seasonal or perennial) associations - families, consisting of breeding and working individuals.
Fan
Part of the feather is formed by a network of thin horny plates (barbs) of the first and second order.
Organism
From lat. organism - I give a slim look
Any living being, an integral system, a carrier of life, possessing a set of properties: metabolism, growth, development, reproduction, etc.
Parapodium
Lateral mobile outgrowths of the body with a tuft of bristles in polychaete worms.
Pathogenic bacteria
From Greek pathos - disease, genesis - origin
These are bacteria that cause severe diseases in humans and animals.
Web
This is a secretion of glands that hardens in air, consisting mainly of protein, close to silk, but much stronger.
Pedipalps
From lat. pēs - leg + palpo - stroke, feel; "clawed tentacles"
Leg tentacles are the mouthparts of arachnids, used to capture and hold prey. They are longer than the chelicerae.
Pinocytosis
From Greek pino - drink; cytosis - cell
Capture and absorption of liquid and substances dissolved in it by the cell.
Planula
From the Latin word planus - flat
A hydroid larva covered with cilia, which subsequently attaches to underwater objects and gives rise to a new polyp.
Placenta
From lat. placenta-cake
The organ of communication between the embryo and the mother's body during intrauterine development in placental mammals; Through the placenta, oxygen and nutrients are supplied to the embryo from the blood of the mother's body and decay products and carbon dioxide are released.
Fruiting body
The outer part - what we usually call the "mushroom" - consists of hyphae, very tightly intertwined.
Polymorphism
From Greek polis - numerous,
morphe - form
The presence within one species of several clearly morphologically different forms (bees, ants, termites): “queen”, “workers”, “soldiers”, etc.
Population
From lat. populus - people, population
The totality of all representatives of a given species occupying a certain space at the same time.
Breed
A collection of domestic animals of the same species, artificially created by man.
Pseudopodia
Cytoplasmic outgrowths in sarcodidae are formed when necessary for movement and food capture.
Chicks
Birds whose chicks emerge from the egg helpless remain in the nest for a long time and are fed by their parents.
Regeneration
From lat. regeneration - restoration, renewal
Restoration of lost or damaged body parts by the body.
Reflex
From lat. reflexus-reflected
The body's response to irritation, carried out through the nervous system.
Rhizoids
From Greek rhiza - root, eidos - species
Body outgrowths serve for attachment to the ground or underwater rocks (in mosses, fern shoots, lichens, some algae and fungi).
Sarcins
From the Latin word sarsine - bundle, knot
Spherical bacteria that look like dense packs.
Segments
From lat. segmentum-segment
One of many homogeneous segments of the body of some animals, as well as one of the homogeneous sections of some organ.
Core
The main tissue located in the center of the stem; performs a storage function.
Symbiosis
From Lat sim - together, bios - life
Forms of coexistence of various organisms.
Taxonomy
From Greek systematic-ordered
A branch of biology whose task is to describe and designate all existing and extinct organisms, as well as their classification.
Sclerotia
From Greek scleros - hard
Thickenings that appear at the site of interweaving of hyphae.
Thallus (thallus)
From Greek thallus - sprout
The vegetative body of algae, fungi, lichens, some bryophytes, undivided into organs (leaf, stem, root) and without true tissues.
Variety
A collection of cultivated plants of the same species, artificially created by man.
Sporangium
From Greek spore-sowing, seed; angeyon - vessel
A unicellular or multicellular organ of asexual reproduction in which spores are formed.
Sporophyte
From Greek spore - sowing, phyton - plant
A plant that produces spores.
Spirilla
From Lat spirilla-bend
Spiral twisted bacterial cells.
Statocyst
From Greek status-standing, cystis-bubble
Organ of balance: a small vesicle of ectodermal origin with sensitive cilia and pebbles inside.
Statolite
From Greek statos - standing, lithos - stone
Small grains of sand that fall into the statocysts and act as “hearing pebbles.”
Streptococci
From Greek streptos-chain, cocos - grain
Bacteria, shaped like balls, form chains of cells
(pathogens of sore throat, scarlet fever).
Warm-blooded animals
Animals that maintain a relatively constant body temperature when the ambient temperature changes (birds, mammals).
Trachea
From Greek tracheilos -throat
Airborne respiratory tubes in some invertebrates.
Tracheids
From Greek tracheilos - throat, eidos - view
Dead spindle-shaped cells with thick membranes that perform conducting and supporting functions.
Turgor
From lat. turgere - to be swollen, filled
The elasticity of plant cells and organs due to the pressure of the cell contents on their elastic walls.
Phagocytosis
From Greek phage - devour, cytosis - cell
Absorption by the cell of large molecules of organic substances and even whole cells.
Compound eyes
Compound eyes, consisting of a large number of individual small ocelli combined together.
Phycocyanin
From Greek phycos - algae, cyanos - dark blue
A water-soluble blue pigment in the chloroplasts of scarlet mushrooms.
Phycoerythrin
From Greek phycos-algae, erythrin-red
A water-soluble red pigment in the chloroplasts of scarlet mushrooms.
Finna
One of the larval stages of development in tapeworms. It looks like a bladder, into the cavity of which one or more formed heads of worms are screwed, developing into adult worms in the final host.
Phytobenthos
From Greek phyton - plant, benthos - depth
Bottom vegetation.
Phytoplankton
From Greek phyton - plant, planktos - wandering
Single-celled algae in the water column.
Phytohormones
From Greek phyton – plant, hormao- excite
Plant hormones that regulate the vital processes of the plant organism.
Phototaxis
From Greek photos - light, taxi - location is ok
Directed movement of organisms, individual cells and their organelles under the influence of light.
Chemosynthesis
from lat. Chemistry and Greek synthetis - compound
The process of formation by some microorganisms of organic substances from carbon dioxide due to the energy obtained from the oxidation of inorganic compounds.
Chelicerae
From Greek words hele - claw, claw and ceras - horn
These are the jaws - the mouthparts of arachnids, used to capture and kill prey.
Chitin
A hard and dense organic substance that is part of the exoskeleton of arthropods.
Chlorella
From Greek chloros - green
Unicellular algae.
Chlorophyll
From Greek chloros - green, phyllon - leaf
A green pigment found in the chloroplasts of green plants.
Cold-blooded animals
Animals whose body temperature changes depending on the ambient temperature (invertebrates, fish, amphibians, reptiles).
Chord
From Greek chord - string
The elastic skeletal axis in chordates is located under the neural tube; performs a supporting function.
Chromatophores
From Greek chromium - color, foros - load-bearing
Organelles of algae that contain pigments that enable photosynthesis.
Cyst
From Greek cystos - bladder
A temporary form of existence of many unicellular organisms, characterized by the presence of a protective shell.
Strain
German strain-tribe, genus
An artificial population of microorganisms characterized by hereditarily fixed productivity.
Evolution
From lat. evolutionary deployment
Irreversible historical process of development of living organisms.
Ectoderm
From Greek ectos - outside, derma - skin
The outer embryo sac of the embryo of multicellular animals.
Embryology
from Greek embryo-fetus and logos-teaching
A branch of biology that studies the embryonic period of development of organisms.
Endoderm
From Greek entos - inside, derma - skin
Inner layer of the embryo of multicellular animals.
Biological terms of cytology
Homeostasis(homo - identical, stasis - state) - maintaining the constancy of the internal environment of a living system. One of the properties of all living things.
Phagocytosis(phago - devour, cytos - cell) - large solid particles. Many protozoans feed by phagocytosis. With the help of phagocytosis, immune cells destroy foreign microorganisms.
Pinocytosis(pino - drink, cytos - cell) - liquids (together with dissolved substances).
Prokaryotes, or prenuclear (pro - do, karyo - nucleus) - the most primitive structure. Prokaryotic cells do not have formalized, no, genetic information is represented by one circular (sometimes linear) chromosome. Prokaryotes lack membrane organelles, with the exception of photosynthetic organelles in cyanobacteria. Prokaryotic organisms include Bacteria and Archaea.
Eukaryotes, or nuclear (eu - good, karyo - nucleus) - and multicellular organisms that have a formed nucleus. They have a more complex organization compared to prokaryotes.
Karyoplasm(karyo - nucleus, plasma - contents) - the liquid contents of the cell.
Cytoplasm(cytos - cell, plasma - contents) - internal environment of the cell. Consists of hyaloplasm (liquid part) and organoids.
Organoid, or organelle(organ - instrument, oid - similar) - a permanent structural formation of a cell that performs certain functions.
In prophase 1 of meiosis, each of the already twisted bichromatid chromosomes closely approaches its homologous one. This is called conjugation (well, confused with conjugation of ciliates).
A pair of homologous chromosomes that come together is called bivalent.
The chromatid then crosses over with a homologous (non-sister) chromatid on the neighboring chromosome (with which the bivalent is formed).
The place where chromatids intersect is called chiasmata. Chiasmus was discovered in 1909 by the Belgian scientist Frans Alphonse Janssens.
And then a piece of the chromatid breaks off at the site of the chiasm and jumps to another (homologous, i.e., non-sister) chromatid.
Gene recombination has occurred. Result: some genes migrated from one homologous chromosome to another.
Before crossing over, one homologous chromosome possessed genes from the maternal organism, and the second from the paternal one. And then both homologous chromosomes possess the genes of both the maternal and paternal organism.
The meaning of crossing over is this: as a result of this process, new combinations of genes are formed, therefore, there is more heritable variability, and therefore there is a greater likelihood of the emergence of new traits that may be useful.
Mitosis– indirect division of a eukaryotic cell.
The main type of cell division in eukaryotes. During mitosis, there is a uniform, equal distribution of genetic information.
Mitosis occurs in 4 phases (prophase, metaphase, anaphase, telophase). Two identical cells are formed.
The term was coined by Walter Fleming.
Amitosis– direct, “incorrect” cell division. Robert Remak was the first to describe amitosis. Chromosomes do not spiral, DNA replication does not occur, spindle threads do not form, and the nuclear membrane does not disintegrate. The nucleus is constricted, with the formation of two defective nuclei, with, as a rule, unevenly distributed hereditary information. Sometimes even the cell does not divide, but simply forms a binuclear cell. After amitosis, the cell loses the ability to undergo mitosis. This term was coined by Walter Fleming.
- ectoderm (outer layer),
- endoderm (inner layer) and
- mesoderm (middle layer).
Common amoeba –
protozoan of the Sarcomastigophora type (Sarcoflagellates), class Rhizomes, order Amoeba.
The body does not have a permanent shape. They move with the help of pseudopods - pseudopodia.
They feed by phagocytosis.
Ciliate slipper- heterotrophic protozoan.
Type of ciliates. The organelles of movement are cilia. Food enters the cell through a special organoid - the cellular mouth opening.
There are two nuclei in a cell: large (macronucleus) and small (micronucleus).
Autolyse, autolysis, self-digestion of tissues, cells or their parts under the action of enzymes in animals, plants and microorganisms.
Autotrophic organisms autotrophs, organisms that use carbon dioxide as the sole or main source of carbon to build their bodies and have both an enzyme system for assimilating carbon dioxide and the ability to synthesize all the components of the cell. Autotrophic organisms include terrestrial green plants, algae, phototrophic bacteria capable of photosynthesis, as well as some bacteria that use the oxidation of inorganic substances - chemoautotrophs.
Adenosine diphosphate, ADP, a nucleotide consisting of adenine, ribose and two phosphoric acid units. Being an acceptor of phosphoryl group in the processes of oxidative and photosynthetic phosphorylation, as well as phosphorylation at the substrate level and a biochemical precursor of ATP - a universal energy accumulator, adenosine diphosphate plays an important role in the energy of a living cell.
Adenosine monophosphate, AMP, adenylic acid, a nucleotide consisting of adenine, ribose and one phosphoric acid residue. In the body, adenine monophosphate is found in RNA, coenzymes and in free form.
Adenosine triphosphate, ATP, adenylpyrophosphoric acid, a nucleotide containing adenine, ribose and three phosphoric acid residues; a universal carrier and main accumulator of chemical energy in living cells, released during the transfer of electrons in the respiratory chain after the oxidative breakdown of organic substances.
Aleurone grains(from the Greek aleuron - flour), grains of storage protein in the cells of the storage tissues of the seeds of legumes, buckwheat, cereals and other plants. They are found in the form of amorphous or crystalline deposits (from 0.2 to 20 microns) of various shapes and structures. They are formed during seed ripening from drying vacuoles and are surrounded by an elementary membrane-tonoplast. Large complex aleurone grains consist of a protein crystalloid and a non-protein part (phytin), some of them containing calcium oxalate crystals. When seeds germinate, aleurone grains swell and undergo enzymatic breakdown, the products of which are used by the growing parts of the embryo.
Allele(from the Greek allelon - each other, mutually), allelomorph, one of the possible structural states of a gene. Any change in the structure of a gene as a result of mutations or due to intragenic recombinations in heterozygotes for two mutant alleles leads to the appearance of new alleles of this gene (the number of alleles for each gene is almost incalculable). The term “allele” was proposed by V. Johansen (1909). Different alleles of the same gene can lead to the same or different phenotypic effects, which has given rise to the concept of multiple allelism.
Amyloplasts(from the Greek amylon - starch and plastos - fashioned), plastids (from the group of leucoplasts) of a plant cell that synthesize and accumulate starch.
Amino acids, organic (carboxylic) acids, usually containing one or two amino groups (-NH 2). About twenty amino acids are usually involved in the construction of protein molecules. The specific sequence of alternation of amino acids in peptide chains, determined by the genetic code, determines the primary structure of the protein.
Amitosis, direct division of the interphase nucleus by constriction without the formation of chromosomes, outside the mitotic cycle. Amitosis can be accompanied by cell division, and can also be limited to nuclear division without division of the cytoplasm, which leads to the formation of bi- and multinucleated cells. Amitosis occurs in various tissues, in specialized cells doomed to death.
Anabolism(from the Greek anabole - rise), assimilation, a set of chemical processes in a living organism aimed at the formation and renewal of the structural parts of cells and tissues. The opposite of catabolism (dissimilation), it involves the synthesis of complex molecules from simpler ones with the accumulation of energy. The energy required for biosynthesis (mainly in the form of ATP) is supplied by catabolic reactions of biological oxidation. Anabolism occurs very intensively during the growth period: in animals - at a young age, in plants - during the growing season. The most important anabolic process of planetary significance is photosynthesis.
Anticodon, a section of a transfer RNA molecule consisting of three nucleotides and recognizing the corresponding section of three nucleotides (codon) in the messenger RNA molecule, with which it interacts complementarily. The specific codon-anticodon interaction that occurs on ribosomes during translation ensures the correct arrangement of amino acids in the synthesized polypeptide chain.
Outbreeding(from English out - outside and breeding - breeding), crossing or a system of crossing unrelated forms of the same species. On the basis of outbreeding, heterotic forms are obtained by conducting interline and interbreeding (intervarietal) crossings. Outbreeding is contrasted with inbreeding.
Autosomes, all chromosomes in the cells of dioecious animals, plants and fungi, with the exception of sex chromosomes.
Acidophilia, the ability of cellular structures to be stained with acidic dyes (eosomin, acid fuchsin, picric acid, etc.) due to the basic (alkaline) properties of the staining structures.
Aerobic organisms aerobes (from the Greek aer - air and bios - life), organisms that can live and develop only in the presence of free oxygen in the environment, which they use as an oxidizing agent. All plants, most protozoa and multicellular animals, almost all fungi, i.e., belong to aerobic organisms. the vast majority of known species of living things.
basal body, kinetosome (corpusculum basale), an intracellular structure of eukaryotes that lies at the base of cilia and flagella and serves as a support for them. The ultrastructure of basal bodies is similar to the ultrastructure of centrioles.
Basophilia, the ability of cellular structures to be stained with basic (alkaline) dyes (azur, pyronine, etc.), due to the acidic properties of the staining components of the cell, mainly RNA. An increase in cell basophilia usually indicates intense protein synthesis occurring in it. Basophilia is characteristic of growing, regenerating, tumor tissues.
Basophils, cells containing granular structures in the protoplasm that are stained with basic dyes. The term “basophils” refers to one of the types of granular leukocytes (granulocytes) in the blood (normally, basophils in humans make up 0.5-1% of all leukocytes), as well as one of the types of cells of the anterior pituitary gland.
Backcross(from English back - back, back and cross - crossing), return crossing, crossing of a first-generation hybrid with one of the parent forms or a form similar in genotype.
Squirrels, proteins, high-molecular organic compounds built from amino acid residues. They play a primary role in life, performing numerous functions in their structure, development and metabolism. The molecular weight of proteins ranges from about 5000 to many millions. The infinite variety of protein molecules (proteins usually include 20 a-L-amino acids), due to the different sequence of amino acid residues and the length of the polypeptide chain, determines the differences in their spatial structure, chemical and physical properties. Depending on the shape of the protein molecule, fibrillar and globular proteins are distinguished, from the functions they perform - structural, catalytic (enzymes), transport (hemoglobin, ceruloplasmin), regulatory (some hormones), protective (antibodies, toxins), etc.; from the composition - simple proteins (proteins consisting only of amino acids) and complex (proteins, which, along with amino acids, include carbohydrates - glycoproteins, lipids - lipoproteins, nucleic acids - nucleoproteins, metals - metalloproteins, etc.); depending on solubility in water, solutions of neutral salts, alkalis, acids and organic solvents - albumins, globulins, glutelins, histones, protamines, prolamines. The biological activity of proteins is due to their unusually flexible, plastic and at the same time strictly ordered structure, which makes it possible to solve problems of recognition at the molecular level, as well as to carry out subtle regulatory effects. The following levels of structural organization of proteins are distinguished: primary structure (sequence of amino acid residues in the polypeptide chain); secondary (laying of the polypeptide chain into a-helical regions and structural formations); tertiary (three-dimensional spatial packaging of a polypeptide chain) and quaternary (association of several individual polypeptide chains into a single structure). The primary structure of the protein is the most stable; the rest are easily destroyed by increased temperature, sudden changes in the pH of the environment and other influences. This violation is called denaturation and, as a rule, is accompanied by a loss of biological properties. The primary structure of a protein determines the secondary and tertiary structure, i.e. self-assembly of a protein molecule. Proteins in the cells of organisms are constantly renewed. The need for their constant renewal underlies metabolism. Nucleic acids play a decisive role in protein biosynthesis. Proteins are the primary products of genes. The sequence of amino acids in proteins reflects the sequence of nucleotides in nucleic acids.
Bivalent(from Latin bi-, in compound words - double, double and valent - strong), a pair of homologous chromosomes connected (conjugated) to each other in meiosis. It is formed at the zygotene stage and persists until anaphase of the first division. In the bivalent between the chromosomes, X-shaped figures are formed - chiasmata, which hold the chromosomes in the complex. The number of bivalents is usually equal to the haploid number of chromosomes.
Bio...(from the Greek bios - life), part of complex words corresponding in meaning to the words “life”, “living organism” (biography, hydrobios) or the word “biological” (biocatalysis, biophysics).
biogenetic law a generalization in the field of relationships between ontogenesis and phylogeny of organisms, established by F. Muller (1864) and formulated by E. Haeckel (1866): the ontogeny of any organism is a brief and condensed repetition (recapitulation) of the phylogeny of a given species.
Nutrients, chemical elements that are constantly included in the composition of organisms and are necessary for their life. Living cells usually contain traces of almost all the chemical elements present in the environment, but about 20 are necessary for life. The most important nutrients are oxygen (accounts for about 70% of the mass of organisms), carbon (18%), hydrogen (10%), nitrogen , potassium, calcium, phosphorus, magnesium, sulfur, chlorine, sodium. These so-called universal biogenic elements are present in the cells of all organisms. Some biogenic elements are important only for certain groups of living beings (for example, boron and other biogenic elements are necessary for plants, vanadium for ascidians, etc.).
Biological membranes(Latin membrana - skin, shell, membrane), structures limiting cells (cellular, or plasma membranes) and intracellular organelles (membranes of mitochondria, chloroplasts, lysosomes, endoplasmic reticulum, etc.). They contain lipids, proteins, heterogeneous macromolecules (glycoproteins, glycolipids) and, depending on the function performed, numerous minor components (coenzymes, nucleic acids, amino acids, carotenoids, inorganic ions, etc.). The main functions of biological membranes are barrier, transport, regulatory and catalytic.
Fermentation, anaerobic enzymatic redox process of transformation of organic substances, through which organisms obtain the energy necessary for life. Compared to processes occurring in the presence of oxygen, fermentation is an evolutionarily earlier and energetically less favorable form of extracting energy from nutrients. Animals, plants and many microorganisms are capable of fermentation (some bacteria, microscopic fungi, protozoa grow only due to the energy obtained during fermentation).
Vacuoles(French vacuole from Latin vacuus - empty), cavities in the cytoplasm of animal and plant cells, bounded by a membrane and filled with liquid. In the cytoplasm of protozoa there are digestive vacuoles containing enzymes and contractile vacuoles that perform the functions of osmoregulation and excretion. Multicellular animals are characterized by digestive and autophagy vacuoles, which are part of the group of secondary lysosomes and contain hydrolytic enzymes.
In plants, vacuoles, derivatives of the endoplasmic reticulum, are surrounded by a semi-permeable membrane - the tonoplast. The entire system of vacuoles in a plant cell is called a vacuome, which in a young cell is represented by a system of tubules and vesicles; As the cell grows and differentiates, they enlarge and merge into one large central vacuole, occupying 70-95% of the volume of the mature cell. Cell sap of the vacuole is a watery liquid with a pH of 2-5, containing organic and inorganic salts (phosphates, oxalates, etc.), sugars, amino acids, proteins, end or toxic metabolic products (tannins, glycosides, alkaloids) dissolved in water. some pigments (for example, anthocyanins). Functions of vacuoles: regulation of water-salt metabolism, maintenance of turgor pressure in the cell, accumulation of low molecular weight water-soluble metabolites, storage substances and removal of toxic substances from metabolism.
Spindle, achromatin spindle, a system of microtubules in a dividing cell that ensures the segregation of chromosomes in mitosis and meiosis. The spindle is formed in prometaphase and disintegrates in telophase.
Cell inclusions, components of the cytoplasm, which are deposits of substances temporarily removed from metabolism or its final products. The specificity of cell inclusions is associated with the specialization of the corresponding cells, tissues and organs. The most common trophic inclusions of cells are drops of fat, lumps of glycogen, and yolk in eggs. In plant cells, cell inclusions are mainly composed of starch and aleurone grains and lipid droplets. Cell inclusions also include secretory granules in the glandular cells of animals, crystals of certain salts (mainly calcium oxalates) in plant cells. A special type of cell inclusions - residual bodies - are products of lysosome activity.
Gas exchange, a set of gas exchange processes between the body and the environment; consists of the body consuming oxygen, releasing carbon dioxide, a small amount of other gaseous substances and water vapor. The biological significance of gas exchange is determined by its direct participation in metabolism, the transformation of the chemical energy of absorbed nutritional products into the energy necessary for the life of the body.
Gamete(from the Greek gamete - wife, gametes - husband), sex cell, reproductive cell of animals and plants. The gamete ensures the transmission of hereditary information from parents to offspring. The gamete has a haploid set of chromosomes, which is ensured by the complex process of gametogenesis. Two gametes fuse during fertilization to form a zygote with a diploid set of chromosomes, which gives rise to a new organism.
Gametogenesis, development of germ cells (gametes).
Gametophyte, the sexual generation in the life cycle of plants developing with alternating generations. Formed from a spore, has a haploid set of chromosomes; produces gametes either in ordinary vegetative cells of the thallus (some algae), or in specialized organs of sexual reproduction - gametangia, oogonia and antheridia (lower plants), archegonia and antheridia (higher plants with the exception of flowering plants).
Haploid(from the Greek haplos - single, simple and eidos - species), an organism (cell, nucleus) with a single (haploid) set of chromosomes, which is denoted by the Latin letter n. In many eukaryotic microorganisms and lower plants, the haploid normally represents one of the stages of the life cycle (haplophase, gametophyte), and in some species of arthropods, males are haploid, developing from unfertilized or fertilized eggs, but in which one of the haploid sets of chromosomes is eliminated. In most animals (and humans), only the germ cells are haploid.
Haplont(from the Greek haplos - single, simple and on - being), an organism in which all cells contain a haploid set of chromosomes, and only the zygote is diploid. Some protozoa (for example, coccidia), fungi (oomycetes), many green algae.
Hemicelluloses, a group of polysaccharides from higher plants that, together with cellulose, make up the cell wall.
Gene(from the Greek genos - genus, origin), hereditary factor, functionally indivisible unit of genetic material; a section of a DNA molecule (in some RNA viruses) that encodes the primary structure of a polypeptide, transport and ribosomal RNA molecules, or interacts with a regulatory protein. The set of genes of a given cell or organism constitutes its genotype. The existence of hereditary discrete factors in germ cells was hypothetically postulated by G. Mendel in 1865 and in 1909. V. Johansen called them genes. Further ideas about genes are associated with the development of the chromosomal theory of heredity.
...genesis(from Greek genesis - origin, emergence), part of complex words meaning origin, process of formation, for example ontogenesis, oogenesis.
Genetic information, information about the properties of an organism that is inherited. Genetic information is recorded by the sequence of nucleotides of nucleic acid molecules (DNA, and in some viruses also RNA). Contains information about the structure of all (about 10,000) enzymes, structural proteins and RNA of the cell, as well as the regulation of their synthesis. Various enzymatic complexes of the cell read the genetic information.
Genetic map of a chromosome, diagram of the relative arrangement of genes located in the same linkage group. To compile a genetic map of chromosomes, it is necessary to identify many mutant genes and conduct numerous crosses. The distance between genes on the genetic map of chromosomes is determined by the frequency of crossing over between them. The unit of distance on the genetic map of chromosomes of meiotically dividing cells is the morganide, corresponding to 1% crossing over.
Genetic code, a unified system for recording hereditary information in nucleic acid molecules in the form of a sequence of nucleotides, characteristic of living organisms; determines the sequence of inclusion of amino acids in the synthesized polypeptide chain in accordance with the nucleotide sequence of the gene. Implementation of the genetic code in living cells, i.e. the synthesis of the protein encoded by the gene is carried out using two matrix processes - transcription and translation. General properties of the genetic code: triplicity (each amino acid is encoded by a triplet of nucleotides); non-overlap (codons of one gene do not overlap); degeneracy (many amino acid residues are encoded by several codons); unambiguity (each individual codon encodes only one amino acid residue); compactness (between codons and mRNA there are no “commas” - nucleotides not included in the codon sequence of a given gene); universality (the genetic code is the same for all living organisms).
Genetic material cell components, the structural and functional unity of which ensures the storage, implementation and transmission of hereditary information during vegetative and sexual reproduction.
Genome(German Genom), a set of genes characteristic of the haploid set of chromosomes of a given type of organism; basic haploid set of chromosomes.
Genotype, genetic (hereditary) constitution of an organism, the totality of all hereditary inclinations of a given cell or organism, including alleles of genes, the nature of their physical linkage in chromosomes and the presence of chromosomal structures.
Gene pool, a set of genes that are present in individuals of a given population, group of populations or species.
Heterogamy, 1) type of sexual process, male and female gametes that merge during fertilization are different in shape and size. Higher plants and multicellular animals, as well as some fungi, are characterized by oogamy; In relation to the copulating and conjugating individuals of a number of protozoa during the sexual process, the term “anisogamy” is used. 2) Change in the function of male and female flowers or their location on the plant (as an anomaly).
Heterozygote, an organism (cell) in which homologous chromosomes carry different alleles (alternative forms) of a particular gene. Heterozygosity, as a rule, determines the high viability of organisms and their good adaptability to changing environmental conditions and is therefore widespread in natural populations.
Heterotrophic organisms heterotrophs, organisms that use exogenous organic substances as a carbon source. As a rule, these same substances also serve as a source of energy for them (organotrophy). Heterotrophic organisms, as opposed to autotrophic organisms, include all animals, fungi, most bacteria, as well as non-chlorophyllous land plants and algae.
Heterochromatin, areas of chromatin that are in a condensed (tightly packed) state throughout the cell cycle. They are intensely stained with nuclear dyes and are clearly visible in a light microscope even during interphase. Heterochromatic regions of chromosomes, as a rule, replicate later than euchromatic ones and are not transcribed, i.e. genetically very inert.
Hyaloplasma, basic plasma, cytoplasmic matrix, complex colorless colloidal system in a cell, capable of reversible transitions from sol to gel.
Glycogen, a branched polysaccharide whose molecules are built from α-D-glucose residues. Molecular weight 10 5 -10 7 . The quickly mobilized energy reserve of many living organisms accumulates in vertebrates mainly in the liver and muscles.
Glycocalyx(from Greek glykys - sweet and Latin callum - thick skin), a glycoprotein complex associated with the outer surface of the plasma membrane in animal cells. The thickness is several tens of nanometers. Extracellular digestion occurs in the glycocalyx, many cell receptors are located in it, and cell adhesion apparently occurs with its help.
Glycolysis, Embden-Meyerhoff-Parnas pathway, enzymatic anaerobic process of non-hydrolytic breakdown of carbohydrates (mainly glucose) to lactic acid. Provides the cell with energy under conditions of insufficient oxygen supply (in obligate anaerobes, glycolysis is the only process that supplies energy), and under aerobic conditions, glycolysis is the stage preceding respiration - the oxidative breakdown of carbohydrates to carbon dioxide and water.
Glycolipids, lipids containing a carbohydrate moiety. Present in the tissues of plants and animals, as well as in some microorganisms. Glycosphingolipids and glycophospholipids are part of biological membranes, play an important role in the phenomena of intercellular adhesion, and have immune properties.
Glycoproteins, glycoproteins, complex proteins containing carbohydrates (from fractions of a percent to 80%). Molecular weight from 15,000 to 1,000,000. Present in all tissues of animals, plants and microorganisms. Glycoproteins that make up the cell membrane are involved in cell ion exchange, immunological reactions, tissue differentiation, intercellular adhesion phenomena, etc.
Globular proteins proteins whose polypeptide chains are folded into compact spherical or ellipsoidal structures (globules). The most important representatives of globular proteins are albumins, globulins, protamines, histones, prolamins, glutelins. Unlike fibrillar proteins, which play mainly a supporting or protective role in the body, many globular proteins perform dynamic functions. Globular proteins include almost all known enzymes, antibodies, some hormones and many transport proteins.
Glucose, grape sugar, one of the most common monosaccharides of the hexose group, is the most important source of energy in living cells.
Homogamety, a characteristic of an organism (or group of organisms) that has a pair or several pairs of homologous sex chromosomes in its chromosome set and, as a result, forms gametes with the same set of chromosomes. The sex represented by such individuals is called homogametic. In mammals, fish and some plant species (hemp, hops, sorrel), homogamety is characteristic of the female sex, and in birds, butterflies and some types of strawberries - for the male sex.
Homozygote, a diploid or polyploid cell (individual), the homologous chromosomes of which carry identical alleles of a particular gene.
Homologous chromosomes contain the same set of genes, are similar in morphological characteristics, and conjugate in meiotic prophase. In a diploid set of chromosomes, each pair of chromosomes is represented by two homologous chromosomes, which can differ in the alleles of the genes they contain and exchange sections during the process of crossing over.
Gram-positive bacteria prokaryotes, whose cells stain positively using the Gram method (able to bind basic dyes - methylene blue, gentian violet, etc., and after treatment with iodine, then alcohol or acetone, retain the iodine-dye complex). In modern literature, gram-positive bacteria include bacteria from the division Firmicutes with the so-called gram-positive type of cell wall structure. Gram-positive bacteria are characterized by: sensitivity to certain antibiotics (not effective on gram-negative bacteria), some features of the composition and structure of the membrane apparatus, the composition of ribosomal proteins, RNA polymerase, the ability to form endospores, true mycelium, and other properties.
Deoxyribonucleic acids, DNA, nucleic acids containing deoxyribose as a carbohydrate component, and adenine (A), guanine (G), cytosine (C), thymine (T) as nitrogen bases. They are present in the cells of any organism and are also part of the DNA molecule. The sequence of nucleotides in an unbranched polynucleotide chain is strictly individual and specific for each natural DNA and represents a code form for recording biological information (genetic code).
Division, a form of reproduction of some organisms and many cells that make up the body of multicellular organisms.
Denaturation(from the Latin de- prefix meaning removal, loss and natura - natural properties), loss of natural (native) configuration by molecules of proteins, nucleic acids and other biopolymers as a result of heating, chemical treatment, etc. is caused by the rupture of non-covalent (weak) bonds in biopolymer molecules (weak bonds maintain the spatial structure of biopolymers). Usually accompanied by a loss of biological activity - enzymatic, hormonal, etc. It can be complete or partial, reversible and irreversible. Denaturation does not break strong covalent chemical bonds, but due to the unfolding of the globular structure, it makes radicals located inside the molecule accessible to solvents and chemical reagents. In particular, denaturation facilitates the action of proteolytic enzymes, giving them access to all parts of the protein molecule. The reverse process is called renaturation.
Differentiation, the emergence of differences between homogeneous cells and tissues, their changes during the development of an individual, leading to the formation of specialized cells, organs and tissues.
Idioblasts(from the Greek idios - special, peculiar), single cells included in any tissue and differing from the cells of this tissue in size, function, shape or internal contents, for example, cells with calcium oxalate crystals or thick-walled supporting cells in the parenchyma of a leaf (sclereids ).
Idiogram(from the Greek idios - special, peculiar and gramma - drawing, line) a unique generalized image of a karyotype in compliance with average quantitative relationships between individual chromosomes and their parts. The idiogram depicts not only the morphological characteristics of chromosomes, but also the features of their primary structure, spiralization, regions of heterochromatin, etc. Comparative analysis of the idiogram is used in karyosystematics to identify and assess the degree of relatedness of different groups of organisms based on the similarities and differences of their chromosome sets.
Isogamy, a type of sexual process in which the fused (copulating) gametes do not differ morphologically, but have different biochemical and physiological properties. Isogamy is widespread in unicellular algae, lower fungi and many protozoa (radiolaria rhizomes, lower gregarines), but is absent in multicellular organisms.
Interphase(from Latin inter -between and Greek phasis -appearance), in dividing cells, the part of the cell cycle between two successive mitoses; in cells that have lost the ability to divide (for example, neurons), the period from the last mitosis to the death of the cell. Interphase also includes the temporary exit of a cell from the cycle (resting state). In interphase, synthetic processes occur, both associated with the preparation of cells for division and ensuring the differentiation of cells and the performance of specific tissue functions. The duration of interphase, as a rule, is up to 90% of the time of the entire cell cycle. A distinctive feature of interphase cells is the despiralized state of chromatin (with the exception of polytene chromosomes of dipterans and some plants, which persist throughout the entire interphase).
Intron(English intron, from intervening sequence - literally intermediate sequence), a section of a gene (DNA) of eukaryotes, which, as a rule, does not carry genetic information related to the synthesis of the protein encoded by this gene; located between other structural gene fragments - exons. The regions corresponding to the intron are presented, along with exons, only in the primary transcript - the precursor of mRNA (pro-mRNA). They are removed from it by special enzymes during mRNA maturation (the exons remain). A structural gene can contain up to several dozen introns (for example, there are 50 introns in the chicken collagen gene) or not contain them at all.
ion channels, supramolecular systems of membranes of a living cell and its organelles, having a lipoprotein nature and ensuring the selective passage of various ions through the membrane. The most common channels are for Na +, K +, Ca 2+ ions; Proton-conducting systems of bioenergy complexes are often classified as ion channels.
Ion pumps, molecular structures built into biological membranes and carrying out the transfer of ions towards a higher electrochemical potential (active transport); function due to the energy of ATP hydrolysis or energy released during the transfer of electrons along the respiratory chain. Active transport of ions underlies the bioenergetics of the cell, the processes of cellular excitation, absorption, and removal of substances from the cell and the body as a whole.
Karyogamy, the fusion of the nuclei of male and female germ cells in the nucleus of the zygote during the process of fertilization. During karyogamy, the pairing of homologous chromosomes, carrying genetic information from the maternal and paternal gametes, is restored.
Mitosis(from karyo nucleus and Greek kinesis - movement), division of the cell nucleus.
Karyology, a branch of cytology that studies the cell nucleus, its evolution and individual structures, including sets of chromosomes in different cells - karyotypes (nuclear cytology). Karyology emerged in the late 19th and early 20th centuries. after establishing the leading role of the cell nucleus in heredity. The ability to establish the degree of relatedness of organisms by comparing their karyotypes determined the development of karyosystematics.
Karyoplasm, karyolymph, nuclear juice, the contents of the cell nucleus in which the chromati are immersed, as well as various intranuclear granules. After extraction of chromatin by chemical agents, the so-called intranuclear matrix is preserved in the karyoplasm, consisting of protein fibrils 2-3 nm thick, which form a framework in the nucleus connecting the nucleoli, chromatin, pore complexes of the nuclear envelope and other structures.
Karyosystematics, a branch of systematics that studies the structures of the cell nucleus in different groups of organisms. Karyosystematics developed at the intersection of systematics with cytology and genetics and usually studies the structure and evolution of the chromosome set - the karyotype.
Karyotype, a set of characteristics of a chromosome set (number, size, shape of chromosomes) characteristic of a particular species. The constancy of the karyotype of each species is supported by the laws of mitosis and meiosis. Changes in karyotype can occur due to chromosomal and genomic mutations. Typically, a description of the chromosome set is made at the stage of metaphase or late prophase and is accompanied by counting the number of chromosomes, morph
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1. What does anatomy study?
Human anatomy is the science of the form, structure and development of the human body in accordance with gender, age and individual characteristics.
Anatomy studies the external forms and proportions of the human body and its parts, individual organs, their design, and microscopic structure. The tasks of anatomy include the study of the main stages of human development in the process of evolution, the structural features of the body and individual organs at various age periods, as well as in environmental conditions.
2. What does physiology study?
Physiology - (from the Greek physis - nature and logos - word, doctrine), the science of life processes and the mechanisms of their regulation in the human body. Physiology studies the mechanisms of various functions of a living organism (growth, reproduction, respiration, etc.), their relationship with each other, regulation and adaptation to the external environment, origin and formation in the process of evolution and individual development of the individual. While solving fundamentally common problems, the physiology of animals and humans and the physiology of plants have differences due to the structure and functions of their objects. Thus, for the physiology of animals and humans, one of the main tasks is the study of the regulatory and integrating role of the nervous system in the body. Prominent physiologists (I.M. Sechenov, N.E. Vvedensky, I.P. Pavlov, A.A. Ukhtomsky, G. Helmholtz, C. Bernard, C. Sherrington, etc.) participated in solving this problem. Plant physiology, which emerged from botany in the 19th century, traditionally studies mineral (root) and aerial (photosynthesis) nutrition, flowering, fruiting, etc. It serves as the theoretical basis of plant growing and agronomy. The founders of Russian plant physiology - A.S. Famintsyn and K.A. Timiryazev. Physiology is related to anatomy, cytology, embryology, biochemistry and other biological sciences.
3. What does hygiene study?
Hygiene - (from the ancient Greek ?gyainYu “healthy”, from?gYaeib “health”) - the science of the influence of the environment on human health.
As a result, hygiene has two objects of study - environmental factors and the body's reaction, and uses the knowledge and methods of physics, chemistry, biology, geography, hydrogeology and other sciences that study the environment, as well as physiology, anatomy and pathophysiology.
Environmental factors are varied and are divided into:
· Physical - noise, vibration, electromagnetic and radioactive radiation, climate, etc.
· Chemical - chemical elements and their compounds.
· Factors of human activity - daily routine, severity and intensity of work, etc.
· Social.
Within the framework of hygiene, the following main sections are distinguished:
· Environmental hygiene - studying the impact of natural factors - atmospheric air, solar radiation, etc.
· Occupational health - studying the impact of the production environment and factors of the production process on humans.
· Communal hygiene - within the framework of which requirements for urban planning, housing, water supply, etc. are developed.
· Food hygiene - studying the meaning and impact of food, developing measures to optimize and ensure food safety (this section is often confused with dietetics).
· Hygiene of children and adolescents - studying the complex effects of factors on a growing organism.
· Military hygiene - aimed at preserving and increasing the combat effectiveness of personnel.
· Personal hygiene is a set of hygienic rules, the implementation of which contributes to the preservation and strengthening of health.
Also some narrow sections: radiation hygiene, industrial toxicology, etc.
Main tasks of hygiene:
· study of the influence of the external environment on the health and performance of people. At the same time, the external environment should be understood as the entire complex complex of natural, social, everyday, production and other factors.
· scientific substantiation and development of hygienic standards, rules and measures to improve the health of the external environment and eliminate harmful factors;
· scientific substantiation and development of hygienic standards, rules and measures to increase the body’s resistance to possible harmful environmental influences in order to improve health and physical development, and increase performance. This is facilitated by a balanced diet, physical exercise, hardening, a properly organized work and rest schedule, and adherence to personal hygiene rules.
4. What factors that disrupt the balance between the environment and the body include toxins?
Each person’s body contains a certain amount of harmful substances, which are called toxins (from the Greek toxikon - poison). They are divided into two large groups.
Exotoxins are harmful substances of chemical and natural origin that enter the body from the external environment with food, air or water. Most often these are nitrates, nitrites, heavy metals and many other chemical compounds present in almost everything that surrounds us. Living in large industrial cities, working in hazardous industries, and even taking medications containing toxic substances are all, to one degree or another, factors in poisoning the body.
Endotoxins are harmful substances that are formed during the life of the body. There are especially many of them in various diseases and metabolic disorders, in particular in poor bowel function, abnormal liver function, sore throat, pharyngitis, influenza, acute respiratory infections, kidney diseases, allergic conditions, even stress.
Toxins poison the body and disrupt its coordinated functioning - most often they undermine the immune, hormonal, cardiovascular and metabolic systems. This leads to complications in the course of various diseases and hinders recovery. Toxins lead to a decrease in the body's resistance, deterioration of general condition and loss of strength.
One theory of aging suggests that it is caused by the accumulation of toxins in the body. They inhibit the functioning of organs, tissues, cells, and disrupt the flow of biochemical processes in them. This ultimately leads to a deterioration in their functions and, as a consequence, to the aging of the entire organism.
Almost any disease is much easier and easier to treat if toxins do not accumulate and are quickly eliminated from the body.
Nature has endowed humans with various systems and organs capable of destroying, neutralizing and removing harmful substances from the body. These are, in particular, the systems of the liver, kidneys, lungs, skin, gastrointestinal tract, etc. In modern conditions, it is becoming increasingly difficult to cope with aggressive toxins, and a person needs additional reliable and effective help.
5. What factors does radiation relate to?
Radioactivity is the instability of the nuclei of some atoms, which manifests itself in their ability to undergo spontaneous transformation (in scientific terms, decay), which is accompanied by the release of ionizing radiation (radiation). The energy of such radiation is quite high, so it is capable of influencing matter, creating new ions of different signs. It is impossible to cause radiation using chemical reactions; it is a completely physical process.
There are several types of radiation:
· Alpha particles are relatively heavy particles, positively charged, and are helium nuclei.
· Beta particles are ordinary electrons.
· Gamma radiation - has the same nature as visible light, but has a much greater penetrating ability.
· Neutrons are electrically neutral particles that arise mainly near an operating nuclear reactor; access there must be limited.
· X-rays are similar to gamma rays, but have less energy. By the way, the Sun is one of the natural sources of such rays, but protection from solar radiation is provided by the Earth’s atmosphere.
Sources of radiation are nuclear installations (particle accelerators, reactors, X-ray equipment) and radioactive substances. They can exist for a considerable time without manifesting themselves in any way, and you may not even suspect that you are near an object of extreme radioactivity.
The body reacts to the radiation itself, and not to its source. Radioactive substances can enter the body through the intestines (with food and water), through the lungs (during breathing) and even through the skin during medical diagnostics using radioisotopes. In this case, internal exposure occurs. In addition, external radiation has a significant impact on the human body, i.e. The source of radiation is outside the body. The most dangerous, of course, is internal radiation.
The effect of radiation on the human body is called irradiation. During this process, radiation energy is transferred to the cells, destroying them. Radiation can cause all sorts of diseases: infectious complications, metabolic disorders, malignant tumors and leukemia, infertility, cataracts and much more. Radiation has a particularly acute effect on dividing cells, so it is especially dangerous for children.
Radiation refers to those factors of physiological impact on the human body for which the human body does not have receptors. He is simply unable to see, hear, touch or taste it.
The absence of direct cause-and-effect relationships between radiation and the body’s response to its effects allows us to constantly and quite successfully exploit the idea of the danger of the influence of small doses on human health.
6. What factors include viruses?
Viruses (derived from the Latin virus - “poison”) are the smallest microorganisms that do not have a cellular structure, a protein synthesizing system and are capable of reproducing only in the cells of highly organized life forms. It was first used to designate an agent capable of causing an infectious disease in 1728.
The appearance of viruses on the evolutionary tree of life is unclear: some may have evolved from plasmids, small DNA molecules that can be passed from one cell to another, while others may have originated from bacteria. In evolution, viruses are an important means of horizontal gene transfer, causing genetic diversity.
Viruses spread in many ways: plant viruses are often transmitted from plant to plant by insects that feed on plant sap, such as aphids; Animal viruses can be spread by blood-sucking insects, such organisms are known as vectors. The influenza virus is spread through respiratory droplets from coughing and sneezing. Norovirus and rotavirus, which commonly cause viral gastroenteritis, are transmitted through the fecal-oral route through contact with contaminated food or water. HIV is one of several viruses that are transmitted through sexual contact and through contaminated blood transfusions. Each virus has a specific host specificity, determined by the types of cells it can infect. The host range may be narrow or, if the virus affects many species, wide.
Viruses, although very small and impossible to see, are the subject of scientific study:
For physicians, viruses are the most common causative agents of infectious diseases: influenza, measles, smallpox, tropical fevers.
For a pathologist, viruses are the etiological agents (cause) of cancer and leukemia, the most common and dangerous pathological processes.
For a veterinarian, viruses are the culprits of epizootics (mass diseases) of foot-and-mouth disease, avian plague, infectious anemia and other diseases affecting farm animals.
For an agronomist, viruses are the causative agents of spotted stripe of wheat, tobacco mosaic, yellow dwarf of potatoes and other diseases of agricultural plants.
For the florist, viruses are the factors that cause the amazing colors of tulips to appear.
For the medical microbiologist, viruses are agents that cause the appearance of toxic (poisonous) varieties of diphtheria or other bacteria, or factors that contribute to the development of bacteria resistant to antibiotics.
For an industrial microbiologist, viruses are pests of bacteria, producers, antibiotics and enzymes.
For a geneticist, viruses are carriers of genetic information.
For a Darwinist, viruses are important factors in the evolution of the organic world.
For an ecologist, viruses are factors involved in the formation of related systems of the organic world.
For a biologist, viruses are the simplest forms of life, possessing all its main manifestations.
For a philosopher, viruses are the clearest illustration of the dialectics of nature, a touchstone for polishing such concepts as living and nonliving, part and whole, form and function.
Viruses are the causative agents of the most important diseases of humans, farm animals and plants, and their importance is increasing all the time as the incidence of bacterial, protozoal and fungal diseases decreases.
7. What is homeostasis?
Life is possible only with a relatively small range of deviations of various characteristics of the internal environment - physico-chemical (acidity, osmotic pressure, temperature, etc.) and physiological (blood pressure, blood sugar, etc.) - from a certain average value. The constancy of the internal environment of a living organism is called homeostasis (from the Greek words homoios - similar, identical and stasis - state).
Under the influence of environmental factors, vital characteristics of the internal environment can change. Then reactions occur in the body aimed at restoring them or preventing such changes. These reactions are called homeostatic. When blood is lost, for example, vasoconstriction occurs, preventing a drop in blood pressure. When sugar consumption increases during physical activity, its release into the blood from the liver increases, which prevents blood sugar levels from falling. With an increase in heat production in the body, the skin vessels dilate, and therefore heat transfer increases, which prevents the body from overheating.
Homeostatic reactions are organized by the central nervous system, which regulates the activity of the autonomic and endocrine systems. The latter already directly affect the tone of blood vessels, metabolic rate, and the functioning of the heart and other organs. The mechanisms of the same homeostatic reaction and their effectiveness can be different and depend on many factors, including hereditary ones.
Homeostasis is also called the preservation of constancy of the species composition and number of individuals in biocenoses, the ability of a population to maintain a dynamic balance of genetic composition, which ensures its maximum viability (genetic homeostasis).
8. What is a cytolemma?
The cytolemma is the universal skin of the cell; it performs barrier, protective, receptor, and excretory functions, transports nutrients, transmits nerve impulses and hormones, and connects cells into tissues.
This is the thickest (10 nm) and most complexly organized cell membrane. It is based on a universal biological membrane, covered on the outside with a glycocalyx, and on the inside, on the cytoplasm side, with a submembrane layer. The glycocalyx (3-4 nm thick) is represented by the outer, carbohydrate regions of complex proteins - glycoproteins and glycolipids that make up the membrane. These carbohydrate chains play the role of receptors that ensure that the cell recognizes neighboring cells and intercellular substance and interacts with them. This layer also includes surface and semi-integral proteins, the functional regions of which are located in the supramembrane zone (for example, immunoglobulins). The glycocalyx contains histocompatibility receptors, receptors for many hormones and neurotransmitters.
The submembrane, cortical layer is formed by microtubules, microfibrils and contractile microfilaments, which are part of the cell cytoskeleton. The submembrane layer maintains the shape of the cell, creates its elasticity, and ensures changes in the cell surface. Due to this, the cell participates in endo- and exocytosis, secretion, and movement.
The cytolemma performs many functions:
1) delimiting (the cytolemma separates, delimits the cell from the environment and ensures its connection with the external environment);
2) recognition by this cell of other cells and attachment to them;
3) recognition by the cell of the intercellular substance and attachment to its elements (fibers, basement membrane);
4) transport of substances and particles into and out of the cytoplasm;
5) interaction with signaling molecules (hormones, mediators, cytokines) due to the presence of specific receptors for them on its surface;
6) ensures cell movement (formation of pseudopodia) due to the connection of the cytolemma with the contractile elements of the cytoskeleton.
The cytolemma contains numerous receptors through which biologically active substances (ligands, signaling molecules, first messengers: hormones, mediators, growth factors) act on the cell. Receptors are genetically determined macromolecular sensors (proteins, glyco- and lipoproteins) built into the cytolemma or located inside the cell and specialized in the perception of specific signals of a chemical or physical nature. Biologically active substances, when interacting with a receptor, cause a cascade of biochemical changes in the cell, transforming into a specific physiological response (change in cell function).
All receptors have a general structural plan and consist of three parts: 1) supramembrane, which interacts with the substance (ligand); 2) intramembrane, carrying out signal transfer and 3) intracellular, immersed in the cytoplasm.
9. What is the significance of the nucleus?
The nucleus is an essential component of the cell (exception: mature red blood cells), where the bulk of the DNA is concentrated.
Two important processes take place in the nucleus. The first of them is the synthesis of the genetic material itself, during which the amount of DNA in the nucleus doubles (for DNA and RNA, see Nucleic acids). This process is necessary so that during subsequent cell division (mitosis) the two daughter cells end up with the same amount of genetic material. The second process is transcription - the production of all types of RNA molecules, which, migrating into the cytoplasm, provide the synthesis of proteins necessary for the life of the cell.
The nucleus differs from the surrounding cytoplasm in its refractive index. That is why it can be seen in a living cell, but usually special dyes are used to identify and study the nucleus. The Russian name “nucleus” reflects the spherical shape most characteristic of this organelle. Such nuclei can be seen in liver cells and nerve cells, but in smooth muscle and epithelial cells the nuclei are oval. There are kernels of more bizarre shapes.
The nuclei that are most dissimilar in shape consist of the same components, i.e. have a general structure plan. In the nucleus there are: nuclear envelope, chromatin (chromosomal material), nucleolus and nuclear juice. Each nuclear component has its own structure, composition and function.
The nuclear envelope includes two membranes located at some distance from each other. The space between the membranes of the nuclear envelope is called perinuclear. There are holes in the nuclear membrane - pores. But they are not end-to-end, but filled with special protein structures called the nuclear pore complex. Through pores, RNA molecules exit the nucleus into the cytoplasm, and proteins move towards them into the nucleus. The nuclear envelope membranes themselves ensure the diffusion of low-molecular compounds in both directions.
Chromatin (from the Greek word chroma - color, paint) is the substance of chromosomes, which in the interphase nucleus are much less compact than during mitosis. When cells are stained, they are painted brighter than other structures.
In the nuclei of living cells, the nucleolus is clearly visible. It has the appearance of a round or irregularly shaped body and clearly stands out against the background of a rather homogeneous nucleus. The nucleolus is a formation that occurs in the nucleus on those chromosomes that are involved in the synthesis of ribosomal RNA. The region of the chromosome that forms the nucleolus is called the nucleolar organizer. Not only RNA synthesis occurs in the nucleolus, but also the assembly of ribosomal subparticles. The number of nucleoli and their sizes may vary. The products of the activity of chromatin and the nucleolus initially enter the nuclear sap (karyoplasm).
For cell growth and reproduction, the nucleus is absolutely necessary. If the main part of the cytoplasm is experimentally separated from the nucleus, then this cytoplasmic lump (cyplast) can exist without a nucleus for only a few days. The nucleus, surrounded by the narrowest rim of cytoplasm (karyoplast), completely retains its viability, gradually ensuring the restoration of organelles and the normal volume of cytoplasm. However, some specialized cells, such as mammalian red blood cells, function for a long time without a nucleus. It is also deprived of platelets - blood platelets, formed as fragments of the cytoplasm of large cells - megakaryocytes. Sperm have a nucleus, but it is completely inactive.
10. What is fertilization?
Fertilization is the fusion of a male reproductive cell (sperm) with a female (ovum), leading to the formation of a zygote, which gives rise to a new organism. Fertilization is preceded by complex processes of maturation of the egg (oogenesis) and sperm (spermatogenesis). Unlike sperm, the egg does not have independent mobility. A mature egg leaves the follicle into the abdominal cavity in the middle of the menstrual cycle at the time of ovulation and enters the fallopian tube thanks to its suction peristaltic movements and the flickering of cilia. The period of ovulation and the first 12-24 hours. after it they are most favorable for fertilization. If it does not happen, then in the following days regression and death of the egg occurs.
During sexual intercourse, sperm (seminal fluid) enters the woman's vagina. Under the influence of the acidic environment of the vagina, some sperm die. The most viable of them penetrate through the cervical canal into the alkaline environment of its cavity and 1.5-2 hours after sexual intercourse reach the fallopian tubes, in the ampullary section of which fertilization occurs. Many sperm rush towards the mature egg, but, as a rule, only one of them penetrates through the zona pellucida covering it, the nucleus of which merges with the nucleus of the egg. From the moment the germ cells merge, pregnancy begins. A single-celled embryo is formed, a qualitatively new cell - a zygote, from which, as a result of a complex development process during pregnancy, the human body is formed. The sex of the unborn child depends on what type of sperm was fertilized in the egg, which is always the carrier of the X chromosome. If the egg was fertilized by a sperm with an X (female) sex chromosome, a female embryo (XX) is created. When an egg is fertilized by a sperm with a Y (male) sex chromosome, a male embryo (XY) develops. There is evidence that sperm containing the Y chromosome are less durable and die faster than sperm containing the X chromosome. Obviously, in this regard, the likelihood of conceiving a boy increases if fertilizing sexual intercourse occurs during ovulation. If sexual intercourse took place several days before ovulation, there is a greater chance that fertilization will occur. Eggs contain sperm containing the X chromosome, i.e. there is a higher chance of having a girl.
The fertilized egg, moving along the fallopian tube, undergoes crushing, passes through the stages of blastula, morula, blastocyst and reaches the uterine cavity on the 5-6th day from the moment of fertilization. At this point, the embryo (embryoblast) is covered on the outside with a layer of special cells - trophoblast, which provides nutrition and implantation (incorporation) into the uterine mucosa, called decidual during pregnancy. The trophoblast secretes enzymes that dissolve the uterine lining, which facilitates the immersion of the fertilized egg into its thickness.
11. What characterizes the crushing stage?
Cleavage is a series of rapid divisions of the zygote without intermediate growth.
After combining the genomes of the egg and sperm, the zygote immediately begins mitotic division - the development of a multicellular diploid organism begins. The first stage of this development is called cleavage. It has a number of features. First of all, in most cases, cell division does not alternate with cell growth. The number of cells of the embryo increases, but its total volume remains approximately equal to the volume of the zygote. During cleavage, the volume of the cytoplasm remains approximately constant, but the number of nuclei, their total volume, and especially the surface area increase. This means that during the period of fragmentation, normal (i.e., characteristic of somatic cells) nuclear-plasma relations are restored. During cleavage, mitoses follow one another especially quickly. This occurs due to the shortening of the interphase: the Gx period is completely eliminated, and the G2 period is also shortened. Interphase practically boils down to the S-period: as soon as the entire DNA is doubled, the cell enters mitosis.
The cells formed during cleavage are called blastomeres. In many animals, they divide synchronously for quite a long time. True, sometimes this synchrony is broken early: for example, in roundworms at the stage of four blastomeres, and in mammals the first two blastomeres divide asynchronously. In this case, the first two divisions usually occur in the meridian planes (pass through the animal-vegetative axis), and the third division - in the equatorial plane (perpendicular to this axis).
Another characteristic feature of cleavage is the absence of signs of tissue differentiation in blastomeres. Cells may already “know” their future fate, but do not yet have neural, muscle or epithelial signs.
12. What is implantation?
physiology cytolemma zygote
Implantation (from Latin in (im) - in, inside and plantatio - planting, transplantation), attachment of the embryo to the wall of the uterus in mammals with intrauterine development and in humans.
There are three types of implantation:
· Central implantation - when the embryo remains in the lumen of the uterus, attaching to its wall either with the entire surface of the trophoblast, or only part of it (in chiropterans, ruminants).
· Eccentric implantation - the embryo penetrates deep into the fold of the uterine mucosa (the so-called uterine crypt), the walls of which then grow together above the embryo and form an implantation chamber isolated from the uterine cavity (in rodents).
· Interstitial implantation - characteristic of higher mammals (primates and humans) - the embryo actively destroys the cells of the uterine mucosa and penetrates into the resulting cavity; The uterine defect heals, and the embryo is completely immersed in the wall of the uterus, where its further development occurs.
13. What is gastrulation?
Gastrulation is a complex process of morphogenetic changes, accompanied by reproduction, growth, directed movement and differentiation of cells, resulting in the formation of germ layers (ectoderm, mesoderm and endoderm) - the sources of the primordia of tissues and organs. The second stage of ontogenesis after fragmentation. During gastrulation, the movement of cell masses occurs with the formation of a two-layer or three-layer embryo from the blastula - the gastrula.
The type of blastula determines the method of gastrulation.
The embryo at this stage consists of clearly separated layers of cells - germ layers: outer (ectoderm) and inner (endoderm).
In multicellular animals, except coelenterates, in parallel with gastrulation or, as in the lancelet, after it, the third germ layer appears - the mesoderm, which is a set of cellular elements located between the ectoderm and endoderm. Due to the appearance of mesoderm, the embryo becomes three-layered.
In many groups of animals, it is at the gastrulation stage that the first signs of differentiation appear. Differentiation (differentiation) is the process of the emergence and growth of structural and functional differences between individual cells and parts of the embryo.
The nervous system, sensory organs, skin epithelium, and tooth enamel are formed from the ectoderm; from the endoderm - the epithelium of the midgut, digestive glands, epithelium of the gills and lungs; from the mesoderm - muscle tissue, connective tissue, circulatory system, kidneys, gonads, etc.
In different groups of animals, the same germ layers give rise to the same organs and tissues.
Methods of gastrulation:
· Intussusception occurs by invagination of the wall of the blastula into the blastocoel; characteristic of most groups of animals.
· Delamination (characteristic of coelenterates) - cells located outside are transformed into the epithelial layer of ectoderm, and the endoderm is formed from the remaining cells. Typically, delamination is accompanied by divisions of blastula cells, the plane of which runs “tangentially” to the surface.
· Immigration - migration of individual cells of the blastula wall into the blastocoel.
· Unipolar - on one section of the blastula wall, usually at the vegetative pole;
· Multipolar - in several areas of the blastula wall.
· Epiboly - the overgrowth of some cells by rapidly dividing other cells or the overgrowth of cells by the internal mass of the yolk (with incomplete crushing).
· Involution is the turning into the embryo of an increasing in size outer layer of cells, which spreads along the inner surface of the cells remaining outside.
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