Biology
course of lectures for students,
students studying in Russian
State educational institution
higher professional education
"Ryazan State Medical University
named after academician I.P. Pavlova
Federal Agency for Health and Social Development"
Department of Histology and Biology
Kalygina T.A. Bryzgalina L.I. Shutov V.I.
Biology
course of lectures for students,
Associate Professor, Ph.D. Bryzgalina L.I.
Associate Professor, Ph.D. Shutov V.I.
Reviewers: Endolov V.V., professor, head. department of ana-
Tomy, physiology and human hygiene Rya-
Zan State University named after.
S. Yesenina
Darmograi V.N., professor, head. department
pharmacognosy with a course in botany.
Il.20, bibliogr.8 BBK 28.0
UDC 57(075.8)
© T.A. Kalygina,
L.I.Bryzgalina,
Shutov V.I.
© State Educational Institution of Higher Professional Education Ryaz. GMU.2008
Modern biology, being a fundamental discipline, plays a primary role in the professional training of various specialists, including doctors.
In the field of medical education, broad biological training of students is necessary for them to obtain fundamental knowledge in the field of biology and medicine, is human-oriented and meets the needs of practical medicine.
The main goal of this work is to form a holistic understanding of the fundamentals of biology, taking into account modern achievements of this rapidly developing branch of science and to assist first-year foreign students in mastering theoretical knowledge in order to achieve the required level in knowledge of educational material.
The material of this course of lectures is presented in the traditional sequence in accordance with the provisions on the theory of biological systems and ideas about the levels of organization of living nature. The material is divided into 16 topics and includes cytology, molecular biology, reproduction and development of organisms, general and medical genetics, the theory of evolution and anthropogenesis.
The basic theoretical material studied in the first year by foreign students of the specialty “general medicine”, “dentistry”, “pharmacy” is presented.
Introduction to the science of biology
Plan
1. Subject of biology. Classification of biological sciences.
2.Methods of studying (research) biology.
3. Basic properties of living beings.
Definition of the concept "life".
4. Levels of organization of living things.
Subject of biology. Classification of biological sciences
The term “biology” is formed from two Greek words (bios - life and logos - teaching).
The term was introduced in 1802 by two naturalists - J.B. Lamarck and G.R. Treviranus, independently of each other.
Biology studies general patterns that are characteristic of all living things and reveal the essence of life, its forms and development.
Biology is a complex science. Sections of the science of biology are classified into the following areas:
1) study of systematic groups (according to objects of study). For example, zoology, botany, virology.
Within these sciences there are narrow directions (or disciplines). For example, in zoology there are protozoology, helminthology, entomology, etc.
2) the study of different levels of organization of living things: molecular biology, histology, etc.
3) properties and manifestations of life of individual organisms. For example, physiology, genetics, ecology.
4) connections with other sciences (as a result of integration of sciences). These are biochemistry, biophysics, biotechnology, radiobiology, etc.
Methods for studying biology
The main methods that are used in biological sciences are:
1) observation and description are the oldest (traditional) method of biology. This method is widely used in our time (in zoology, botany, cytology, ecology, etc.)
2) comparison, i.e. The comparative method makes it possible to find similarities and differences, general patterns in the structure of organisms.
3) experience or experiment. For example, the experiments of G. Mendel or the work of I. P. Pavlov in physiology.
4) modeling – creating a specific model or processes and studying them. For example, modeling the conditions and processes (inaccessible to observation) of the origin of life.
5) historical method - studying the patterns of appearance and development of organisms
Basic properties of living things
Living beings differ from non-living bodies in a number of properties. The main properties of living things include:
Specific organization .
Living organisms have the necessary structures that ensure their vital functions.
The specific organization of living beings is also manifested in particular chemical composition. Of the chemical elements, the largest share is oxygen, carbon, hydrogen, and nitrogen. Together they make up more than 98% of the chemical composition. These elements form complex organic compounds in living organisms - proteins, fats, nucleic acids, carbohydrates, which are not found in inanimate nature.
Metabolism and energy.
Organisms constantly exchange substances and energy with the environment - this is a prerequisite for existence.
Metabolism and energy consist of 2 processes:
a) synthesis or assimilation, or plastic exchange (with energy absorption).
b) decay or dissimilation, or energy exchange (with the release of energy)
Homeostasis is the maintenance of a constant internal environment.
Complex self-regulating processes take place in living beings, which occur in a strictly defined order and are aimed at maintaining the constancy of the internal environment (for example, the constancy of the chemical composition). In this case, the body is in a state of dynamic equilibrium (i.e., mobile equilibrium), which is important when existing in changing environmental conditions.
Reproduction.
Reproduction is the ability of organisms to reproduce their own kind. Every living creature has a limited life span, but by leaving behind offspring, it ensures the continuity and continuity of life.
The ability to develop is changing objects of living nature.
Individual development (ontogenesis) - the development of an individual in most cases begins from the zygote (fertilized egg) or from the division of the mother cell until the end of life. During ontogenesis, growth, differentiation of cells, tissues, organs, and interaction of individual parts occur. The lifespan of individuals is limited by aging processes leading to death.
Phylogenesis is the historical development of the world of living organisms.
Phylogenesis is the irreversible and directed development of living nature, which is accompanied by the formation of new species and the progressive complication of life. The result of historical development is the diversity of living beings.
Irritability.
Irritability is the body’s ability to respond to influences with certain reactions. The form of manifestation of irritability is movement.
In plants - tropism (for example, a change in the position of leaves in space due to illumination - phototropism).
Single-celled animals have taxis.
Multicellular reactions to stimulation are carried out using the nervous system and are called reflexes.
Heredity.
Heredity is the property of organisms to transmit from generation to generation the characteristic characteristics of a species with the help of carriers of hereditary information, DNA and RNA molecules.
Variability.
Variability is the property of organisms to acquire new characteristics. Variation creates a variety of material for natural selection.
Based on the properties of living things, scientists are trying to define the concept of “life”. The current state of development of biology best corresponds to the definition of life given by the scientist - biophysicist M.V. Volkenshtein: “Living bodies are open, self-regulating, self-reproducing systems, built from polymers - proteins and nucleic acids and maintaining their existence as a result of the exchange of substances and energy with environment."
This definition includes signs of living things. Each cell and the organism as a whole is a system, i.e. represent a set of interacting, ordered structures (organelles, tissue cells, organs). Living beings are open systems that are in a state of dynamic equilibrium with the external environment. Living beings carry out a continuous exchange of substances and energy with the environment (absorption and excretion, assimilation and dissimilation).
Plan
1.Cell theory.
2. Cell structure.
3. Cell evolution.
Cell theory.
In 1665 R. Hooke was the first to discover plant cells. In 1674 A. Leeuwenhoek discovered the animal cell. In 1839 T. Schwann and M. Schleiden formulated the cell theory. The main tenet of the cell theory was that the cell is the structural and functional basis of living systems. But they mistakenly believed that cells are formed from structureless matter. In 1859 R. Virchow proved that new cells are formed only by dividing the previous ones.
Basic principles of cell theory :
1) The cell is the structural and functional unit of all living things. All living organisms are made up of cells.
2) All cells are basically similar in chemical composition and metabolic processes.
3) New cells are formed by dividing existing ones.
4) All cells store and implement hereditary information in the same way.
5) The life activity of a multicellular organism as a whole is determined by the interaction of its constituent cells.
Cell structure
Based on their structure, there are 2 types of cells:
Prokaryotes
Eukaryotes
Prokaryotes include bacteria and blue-green algae. Prokaryotes differ from eukaryotes in the following: they do not have membrane organelles found in a eukaryotic cell (mitochondria, endoplasmic reticulum, lysosomes, Golgi complex, chloroplasts).
The most important difference is that they do not have a membrane-surrounded nucleus. Prokaryotic DNA is represented by one folded circular molecule. Prokaryotes also lack centrioles of the cell center, so they never divide by mitosis. They are characterized by amitosis - direct rapid division.
Eukaryotic cells are cells of unicellular and multicellular organisms. They consist of three main components:
The cell membrane that surrounds the cell and separates it from the external environment;
Cytoplasm containing water, mineral salts, organic compounds, organelles and inclusions;
The nucleus, which contains the genetic material of the cell.
Outer cell membrane
1 – polar head of the phospholipid molecule
2 – fatty acid tail of the phospholipid molecule
3 – integral protein
4 – peripheral protein
5 – semi-integral protein
6 – glycoprotein
7 - glycolipid
The outer cell membrane is inherent in all cells (animal and plant), has a thickness of about 7.5 (up to 10) nm and consists of lipid and protein molecules.
Currently, the fluid-mosaic model of cell membrane construction is widespread. According to this model, lipid molecules are arranged in two layers, with their water-repellent ends (hydrophobic - fat-soluble) facing each other, and their water-soluble (hydrophilic) ends facing the periphery. Protein molecules are embedded in the lipid layer. Some of them are located on the outer or inner surface of the lipid part, others are partially submerged or penetrate the membrane through.
Functions of membranes :
Protective, border, barrier;
Transport;
Receptor - carried out due to proteins - receptors, which have a selective ability to certain substances (hormones, antigens, etc.), enter into chemical interactions with them, conduct signals into the cell;
Participate in the formation of intercellular contacts;
Provide movement of some cells (amoeba movement).
Animal cells have a thin layer of glycocalyx on top of the outer cell membrane. It is a complex of carbohydrates with lipids and carbohydrates with proteins. The glycocalyx is involved in intercellular interactions. The cytoplasmic membranes of most cell organelles have exactly the same structure.
In plant cells, outside the cytoplasmic membrane. there is a cell wall consisting of cellulose.
Transport of substances across the cytoplasmic membrane .
There are two main mechanisms for substances entering or exiting the cell:
1.Passive transport.
2.Active transport.
Passive transport of substances occurs without energy consumption. An example of such transport is diffusion and osmosis, in which the movement of molecules or ions occurs from an area of high concentration to an area of lower concentration, for example, water molecules.
Active transport - in this type of transport, molecules or ions penetrate the membrane against a concentration gradient, which requires energy. An example of active transport is the sodium-potassium pump, which actively pumps sodium out of the cell and absorbs potassium ions from the external environment, transporting them into the cell. The pump is a special membrane protein that drives ATP.
Active transport ensures the maintenance of constant cell volume and membrane potential.
Transport of substances can be carried out by endocytosis and exocytosis.
Endocytosis is the penetration of substances into the cell, exocytosis is from the cell.
During endocytosis, the plasma membrane forms invaginations or protrusions, which then envelop the substance and, when released, turn into vesicles.
There are two types of endocytosis:
1) phagocytosis - absorption of solid particles (phagocyte cells),
2) pinocytosis - absorption of liquid material. Pinocytosis is characteristic of amoeboid protozoa.
By exocytosis, various substances are removed from the cells: undigested food remains are removed from the digestive vacuoles, and their liquid secretion is removed from the secretory cells.
Cytoplasm –(cytoplasm + nucleus form protoplasm). Cytoplasm consists of a watery ground substance (cytoplasmic matrix, hyaloplasm, cytosol) and various organelles and inclusions contained in it.
Inclusions– waste products of cells. There are 3 groups of inclusions - trophic, secretory (gland cells) and special (pigment) significance.
Organelles – These are permanent structures of the cytoplasm that perform certain functions in the cell.
Organelles of general importance and special ones are distinguished. Specials are found in most cells, but are present in significant quantities only in cells that perform a specific function. These include microvilli of intestinal epithelial cells, cilia of the epithelium of the trachea and bronchi, flagella, myofibrils (providing muscle contraction, etc.).
Organelles of general importance include the ER, Golgi complex, mitochondria, ribosomes, lysosomes, centrioles of the cell center, peroxisomes, microtubules, microfilaments. In plant cells there are plastids and vacuoles. Organelles of general importance can be divided into organelles having a membrane and non-membrane structure.
Organelles with a membrane structure are either double-membrane or single-membrane. Mitochondria and plastids are classified as double-membrane cells. Single-membrane cells include the endoplasmic reticulum, Golgi complex, lysosomes, peroxisomes, and vacuoles.
Organelles that do not have membranes: ribosomes, cell center, microtubules, microfilaments.
Mitochondria – these are organelles of round or oval shape. They consist of two membranes: internal and external. The inner membrane has projections called cristae, which divide the mitochondria into compartments. The compartments are filled with a substance - matrix. The matrix contains DNA, mRNA, tRNA, ribosomes, calcium and magnesium salts. Autonomous protein biosynthesis occurs here. The main function of mitochondria is the synthesis of energy and its accumulation in ATP molecules. New mitochondria are formed in the cell as a result of the division of old ones.
Plastids – organelles found primarily in plant cells. They come in three types: chloroplasts, which contain a green pigment; chromoplasts (red, yellow, orange pigments); leucoplasts (colorless).
Chloroplasts, thanks to the green pigment chlorophyll, are able to synthesize organic substances from inorganic ones using the energy of the sun.
Chromoplasts give bright colors to flowers and fruits.
Leukoplasts are able to accumulate reserve nutrients: starch, lipids, proteins, etc.
Endoplasmic reticulum ( EPS ) is a complex system of vacuoles and channels that are bounded by membranes. There are smooth (agranular) and rough (granular) EPS. Smooth does not have ribosomes on its membrane. It contains the synthesis of lipids, lipoproteins, accumulation and removal of toxic substances from the cell. Granular ER has ribosomes on its membranes in which proteins are synthesized. The proteins then enter the Golgi complex and from there out.
Golgi complex (Golgi apparatus) It is a stack of flattened membrane sacs - cisterns and an associated system of bubbles. A stack of cisternae is called a dictyosome.
Functions of the Golgi complex : protein modification, polysaccharide synthesis, substance transport, cell membrane formation, lysosome formation.
Lysosomes – They are membrane-surrounded vesicles containing enzymes. They carry out intracellular breakdown of substances and are divided into primary and secondary. Primary lysosomes contain enzymes in an inactive form. After various substances enter the organelles, enzymes are activated and the digestion process begins - these are secondary lysosomes.
Peroxisomes They look like bubbles bounded by one membrane. They contain enzymes that break down hydrogen peroxide, which is toxic to cells.
Vacuoles – These are organelles of plant cells containing cell sap. Cell sap may contain spare nutrients, pigments, and waste products. Vacuoles participate in the creation of turgor pressure and in the regulation of water-salt metabolism.
Ribosomes – organelles consisting of large and small subunits. They can be located either on the ER or located freely in the cell, forming polysomes. They consist of rRNA and protein and are formed in the nucleolus. Protein biosynthesis occurs in ribosomes.
Cell center – found in the cells of animals, fungi, and lower plants and is absent in higher plants. It consists of two centrioles and a radiate sphere. The centriole has the appearance of a hollow cylinder, the wall of which consists of 9 triplets of microtubules. When cells divide, they form mitotic spindle threads, which ensure the separation of chromatids in anaphase of mitosis and homologous chromosomes during meiosis.
Microtubules – tubular formations of various lengths. They are part of centrioles, mitotic spindles, flagella, cilia, perform a supporting function, and promote the movement of intracellular structures.
Microfilaments – filamentous thin formations located throughout the cytoplasm, but there are especially many of them under the cell membrane. Together with microtubules, they form the cytoskeleton of the cell, determine the flow of cytoplasm, intracellular movements of vesicles, chloroplasts and other organelles.
Cell evolution
There are two stages in the evolution of a cell:
1. Chemical.
2.Biological.
The chemical stage began about 4.5 billion years ago. Under the influence of ultraviolet radiation, radiation, lightning discharges (energy sources), the formation of first simple chemical compounds - monomers, and then more complex ones - polymers and their complexes (carbohydrates, lipids, proteins, nucleic acids) occurred.
The biological stage of cell formation begins with the appearance of probionts - isolated complex systems capable of self-reproduction, self-regulation and natural selection. Probionts appeared 3-3.8 billion years ago. The first prokaryotic cells, bacteria, originated from probionts. Eukaryotic cells evolved from prokaryotes (1-1.4 billion years ago) in two ways:
1) Through symbiosis of several prokaryotic cells - this is a symbiotic hypothesis;
2) By invagination of the cell membrane. The essence of the invagination hypothesis is that the prokaryotic cell contained several genomes attached to the cell wall. Then invagination occurred - invagination, unlacing of the cell membrane, and these genomes turned into mitochondria, chloroplasts, and the nucleus.
Cell differentiation and specialization .
Differentiation is the formation of different types of cells and tissues during the development of a multicellular organism. One hypothesis links differentiation to gene expression during individual development. Expression is the process of turning on certain genes into work, which creates conditions for the targeted synthesis of substances. Therefore, tissues develop and specialize in one direction or another.
Plan
1.Structure and functions of the cell nucleus.
2.Chromatin and chromosomes.
3. Cellular and mitotic cell cycles.
4. Cell proliferation.
Structure and functions of the cell nucleus .
The nucleus is an essential part of a eukaryotic cell. The main function of the nucleus is to store genetic material in the form of DNA and transfer it to daughter cells during cell division. In addition, the nucleus controls protein synthesis and controls all vital processes of the cell. (in a plant cell the nucleus was described by R. Brown in 1831, in an animal cell by T. Schwann in 1838)
Most cells have one nucleus, usually round in shape, less often irregular in shape.
The size of the nucleus ranges from 1 µm (in some protozoa) to 1 mm (in the eggs of fish and amphibians).
There are binucleate cells (liver cells, ciliates) and multinucleate cells (in the cells of transversely striated muscle fibers, as well as in the cells of a number of species of fungi and algae).
Some cells (erythrocytes) are nuclear-free; this is a rare phenomenon and is secondary in nature.
The core includes:
1) nuclear membrane;
2) karyoplasm;
3) nucleolus;
4) chromatin or chromosomes. Chromatin is located in the non-dividing nucleus, chromosomes are in the mitotic nucleus.
The core shell consists of two membranes (outer and inner). The outer nuclear membrane connects to the membrane channels of the ER. Ribosomes are located on it.
The nuclear membranes have pores (3000-4000). Through nuclear pores, various substances are exchanged between the nucleus and the cytoplasm.
Karyoplasm (nucleoplasm) is a jelly-like solution that fills the space between the nuclear structures (chromatin and nucleoli). It contains ions, nucleotides, enzymes.
The nucleolus, usually spherical in shape (one or more), is not surrounded by a membrane, contains fibrillar protein threads and RNA.
Nucleoli are not permanent formations; they disappear at the beginning of cell division and are restored after its completion. Nucleoli are present only in non-dividing cells. In the nucleoli, ribosomes are formed and nuclear proteins are synthesized. The nucleoli themselves are formed in areas of secondary chromosome constrictions (nucleolar organizers). In humans, nucleolar organizers are located on chromosomes 13, 14, 15, 21 and 22.
Chromatin and chromosomes
Chromatin is a despiralized form of chromosome existence. In a despiralized state, chromatin is found in the nucleus of a nondividing cell.
Chromatin and chromosomes interchange into each other. In terms of chemical organization, both chromatin and chromosomes do not differ. The chemical basis is deoxyribonucleoprotein - a complex of DNA with proteins. With the help of proteins, multi-level packaging of DNA molecules occurs, while chromatin acquires a compact shape. For example, in a despiralized (extended) state, the length of the DNA molecule of a human chromosome reaches about 6 cm, which is approximately 1000 times greater than the diameter of the cell nucleus. Despite the fact that in non-dividing cells chromatin is in a despiralized state, nevertheless, its individual sections are spiralized, i.e. chromatin is heterogeneous in structure.
Spiralized regions of chromatin are called heterochromatin, and despiralized regions are called euchromatin. Transcription processes (mRNA synthesis) occur in areas of euchromatin.
Heterochromatin is an inactive region of chromatin; transcription does not occur here.
At the beginning of cell division, chromatin twists (spirals) and forms chromosomes, which are clearly visible under a light microscope. This means that the chromosome is supercoiled chromatin. Spiralization reaches its maximum in metaphase of mitosis. Each metaphase chromosome consists of two sister chromatids. Chromatids contain identical DNA molecules, which are formed during the doubling (replication) of DNA during the synthetic period of interphase. The chromatids are connected to each other in the region of the primary constriction - the centromere. Centromeres divide the chromosomes into two arms. Depending on the location of the centromere, the following types of chromosomes are distinguished:
1) metacentric (equal arms);
2) submetacentric (unequal shoulders);
3) acrocentric (rod-shaped);
4) satellite (have a secondary constriction, which separates a small section of the chromosome, called a satellite).
The number, size and shape of chromosomes in cell nuclei are important signs of each species. The set of chromosomes of somatic cells of a given species is called a karyotype.
Cell life cycle
G1 – presynthetic period
S – synthetic period
G2 – post-synthetic period
G0 – period of proliferative rest
The cell cycle or life cycle of a cell is the set of processes occurring in a cell from the 1st division (its appearance as a result of division) to the next division or until the death of the cell.
The mitotic cycle is the period of cell preparation for division and the division itself. The mitotic cycle of a cell consists of interphase and mitosis. Interphase divided into 3 periods:
1. Presynthetic or postmitotic.
2. Synthetic.
3. Postsynthetic or premitotic.
The duration of the mitotic cycle ranges from 10 to 50 hours. During the presynthetic period, the cell performs its functions and increases in size, i.e. actively grows, the number of mitochondria and ribosomes increases, proteins and nucleotides are synthesized, energy is accumulated in the form of ATP, and RNA is synthesized.
Chromosomes are thin strands of chromatin, each consisting of one chromatid. The content of genetic material in a cell is designated as follows: With- amount of DNA in one chromatid, n – set of chromosomes.
A cell in G 1 contains a diploid set of chromosomes, each chromosome has one chromatid (2c DNA of 2n chromosomes).
In S - During this period, replication of DNA molecules occurs and their content in the cell doubles, each chromosome becomes bichromatic (i.e., the chromatid completes its own similar one). The genetic material becomes 4c2n, the centrioles of the cell also double.
The duration of the S-period in mammals is 6-10 hours. The cell continues to perform its specific functions.
In the G 2 period, the cell prepares for mitosis: energy accumulates, all synthetic processes die out, the cell stops performing basic functions, proteins accumulate to build the division spindle. The content of genetic information does not change (4с2n). The duration of this period is 3-6 hours.
Mitosis - This is indirect division, the main method of division of somatic cells.
Mitosis is a continuous process and is conventionally divided into 4 stages: prophase, metaphase, anaphase, telophase. The first and last ones are the longest. The duration of mitosis is 1-2 hours.
1. Prophase . At the beginning of prophase, the centrioles diverge to the poles of the cell; microtubules begin to form from the centrioles, which stretch from one pole to the other and towards the equator of the cell, forming a spindle. . By the end of prophase, the nucleoli and nuclear membrane dissolve. The spindle threads are attached to the centromeres of the chromosomes, the chromosomes spiral and rush towards the center of the cell. The content of genetic information does not change (4с2n).
2.Metaphase . Duration 2-10 min. Short phase, chromosomes are located at the equator of the cell, and the centromeres of all chromosomes are located in the same plane - the equatorial one. Gaps appear between the chromatids. In the region of the centromeres, there are small disc-shaped structures on both sides - kinetochores. From them, just like from the centrioles, microtubules extend, which are located between the filaments of the spindle.
There is a point of view that it is kinetochore microtubules that force the centromeres of all chromosomes to line up in the equator region. This is the stage of greatest spiralization of chromosomes, when they are most convenient to study. The content of genetic information does not change (4с2n).
3. Anaphase lasts 2-3 minutes, the shortest stage. In anaphase, centromeres split and chromatids separate. After separation, one chromatid (sister chromosome) begins to move towards one pole, and the other half begins to move towards the other.
It is assumed that the movement of chromatids is caused by the sliding of kinetochore tubes along the microtubules of centrioles. It is microtubules that generate the force that causes chromatid separation. According to another version, the filaments of the spindle melt and carry the chromatids with them.
The cell contains two diploid sets of chromosomes - 4c4n (each pole has 2c2n).
4. Telophase . During telophase, the nuclei of daughter cells are formed, chromosomes despiral, nuclear membranes are built, and nucleoli appear in the nucleus.
Cytokinesis– division of the cytoplasm occurs at the end of telophase.
In animal cells, the cytoplasmic membrane invaginates inward. The cell membranes close together, completely separating the two cells. In plant cells, a cell plate located in the equatorial plane is formed from the membranes of Golgi vesicles. The cell plate, expanding completely, separates the two daughter cells. Each cell contains 2c 2n.
Mitosis
The meaning of mitosis.
1.Maintaining a constant number of chromosomes. Mitosis is a hereditarily equal division.
The biological significance of mitosis is the strictly identical distribution of sister chromosomes between daughter cells, which ensures the formation of genetically equivalent cells and maintains continuity in a number of cell generations.
2. Ensuring the growth of the body.
3. Replacement of worn-out cells, damaged tissues, regeneration of lost parts.
Thus, in humans, skin cells, intestinal epithelium, lung epithelium, blood cells are replaced - a total of 1011 cells per day.
4. Mitosis underlies asexual reproduction.
Amitosis - direct cell division by lacing the nucleus without spiralization results in an even distribution of genetic material between the daughter nuclei. After amitotic division, cells cannot divide mitotically. Cells divide by amitosis during inflammatory processes and malignant growth. Amitosis occurs in the cells of some specialized tissues, for example, in striated muscles and connective tissue.
Cell proliferation
Proliferation- an increase in the number of cells through mitosis, which leads to tissue growth and renewal. The intensity of proliferation is regulated by substances that are produced both inside cells and away from cells. Modern data indicate that kelons are one of the regulators of proliferation at the cellular level. Keylons– hormone-like substances that are polypeptides or glycoproteins. They are formed by all cells and inside the cells of higher organisms, and are found in various body fluids, including urine. Keylons suppress the mitotic activity of cells. They are also involved in the regulation of tissue growth, wound healing, and immune reactions.
Hormonal mechanisms– distant regulators of proliferation at the organismal level. For example, the level of red blood cells in high mountain areas increases due to the secretion of the hormone erythropoietin in specialized kidney cells. Residents of highlands have a higher number of red blood cells than people living on the plain.
In addition, there are hypotheses about the reasons that prompt a cell to divide. For example:
- volumetric– the cell, having reached a certain volume, divides. Nuclear-cytoplasmic ratios change (from 1/6 to 1/69),
- "mitogenetic ray" hypothesis ». Dividing cells stimulate nearby cells to undergo mitosis.
- "wound hormone" hypothesis » . Damaged cells release special substances that promote mitosis of undamaged cells.
Reproduction of organisms
Plan
1. Forms of reproduction of living organisms.
2. Gametogenesis.
Gametogenesis
Gametogenesis - development of germ cells - gametes . The development of male reproductive cells is called - spermatogenesis, and women's - ovogenesis.
Spermatogenesis
Oogenesis (oogenesis)
Cellules germinales primordiales - primary germ cell; Ovogonie- ovogonia; Ovocyte de premier ordre – oocyte of the first order; Meiose 1 – meiosis 1; Ovocyte de deuxieme ordre – oocyte of the second order; Premier globule polaire - first directional body; Meiose 11- meiosis 11; Second globule polaire - second directional body; Ovule (haploide) – egg (haploid); Ovaire-ovary; Follicule primaire - growing follicle; Follicule a maturite – mature follicle; Ovulation- ovulation; Follicule rompu - ruptured follicle; Corps jaune - yellow body.
Oogenesis occurs in the ovary and includes periods of reproduction, growth, and maturation. During the period of reproduction from the rudimentary cells of gonoblasts, the number of diploid germ cells - oogonia - increases through mitosis. This period ends before birth. Most of the cells die.
Growth period - the cell volume increases hundreds of times due to the accumulation of yolk and a first-order oocyte is formed. DNA replication occurs (4c 2n).
Oocytes of the first order enter prophase of the first division of meiosis. This phase in humans lasts until puberty. From the moment of puberty, the first meiotic division is completed and a small cell is formed - a guide body and a large oocyte of the second order (2c 1n). After the second division of meiosis, the second-order oocyte divides again and 1 ovotide (haploid egg) and a guide body are formed. The first directional body is also divided into two. The resulting guide cells then disappear.
Sciences studying biology
Acarology is the science that studies mites.
Anatomy is a branch of biology and specifically morphology that studies the structure of the body of organisms and their parts at a level above the cellular level.
Algology is a branch of biology that studies algae. Previously, all algae were classified as plants, and therefore algology was considered a branch of botany.
Anthropology is the biological science of the origin and evolution of the physical organization of man and the human races.
Arachnalogy is the science of studying spiders.
Bacteriology (from the Greek bakteria - stick and logos - word), the science of the smallest, invisible to the naked eye.
Biogeography is the science of the geographical distribution and distribution of organisms and their communities on Earth.
Bioinformatics is a set of methods and approaches, including: mathematical methods of computer analysis in comparative genomics (genomic bioinformatics).
Biometrics involves a system for recognizing people based on one or more physical or behavioral traits. In the field of information technology, biometrics are used as a form of access identifier management and access control.
Bionics (from ancient Greek βίον - living) is an applied science about the application in technical devices and systems of the principles of organization, properties, functions and structures of living nature, that is, the forms of living things in nature and their industrial analogues.
Biospeleology, speleobiology is a branch of biology that deals with the study of organisms living in caves.
Biophysics is the science of physical processes occurring in biological systems at different levels of organization, and of the influence of various physical factors on biological objects. Biophysics is designed to identify connections between the physical mechanisms underlying the organization of living objects and the biological characteristics of their life.
Biochemistry (biological or physiological chemistry) is the science of the chemical composition of living cells and organisms and the chemical processes underlying their life activity.
Botany is the science of plants.
Biomechanics is a branch of natural sciences that studies, on the basis of models and methods of mechanics, the mechanical properties of living tissues, individual organs and systems, or the organism as a whole, as well as the mechanical phenomena occurring in them.
Biocenology (from biocenosis and ...logy), the central section of ecology, studying the patterns of life of organisms in biocenoses, their population structure, energy flows and the circulation of substances.
Bryology (Greek, from bryon - moss, and logos - word) is the science of studying mosses.
Virology is a branch of microbiology that studies viruses (from the Latin word virus - poison).
Helmitology is the science that studies worms.
Genetics is the science of the laws of heredity and variability.
Geobotany is a branch of biology at the intersection of botany, geography and ecology. This is the science of the Earth’s vegetation, the totality of plant communities (phytocenoses), their composition, and structure.
Herpetology. (from the Greek herpeton - reptile and...logy), a section of zoology that studies reptiles and amphibians.
Hydrobiology is the science of life and biological processes in water, one of the biological disciplines.
Histology is a branch of biology that studies the structure, vital activity and development of tissues of living organisms.
Dendrology" is a branch of botany, the subject of study of which is woody plants: in addition to trees, these are also shrubs, subshrubs, dwarf shrubs, tree-like vines, as well as creeping woody plants.
Zoology (from ancient Greek ζῷον - animal + λόγος - study) is a biological science that studies representatives of the animal kingdom. Zoology studies the physiology, anatomy, embryology, ecology, and phylogeny of animals.
Ichthyology (from the Greek ichthýs - fish and ... Logia) is a branch of vertebrate zoology that studies fish, their structure, the functions of their organs, lifestyle at all stages of development, the distribution of fish in time and space, their systematics, evolution.
Coleopterology (from Coleoptera, Beetles, and Greek -λογία, ...logy) is a branch of entomology that studies beetles (insects from the order Coleoptera, lat. Coleoptera).
Xenobiology is a subfield of synthetic biology that studies the creation and control of biological devices and systems.
Lepidopterology is a branch of entomology that studies representatives of the order Lepidoptera (butterflies).
Lichenology (from the Greek λειχήν - lichen, lichen) - the science of lichens, a branch of botany.
Mycology (from ancient Greek μύκης - mushroom) is a branch of biology, the science of mushrooms.
Myrmecology (from ancient Greek μύρμηξ “ant” and λόγος “study”) is the science that studies ants.
Paleontology (from ancient Greek παλαιοντολογία) is the science of organisms that existed in past geological periods and were preserved in the form of fossil remains, as well as traces of their vital activity.
Palynology is a complex of branches of science (primarily botany) associated with the study of pollen grains and spores.
Radiation biology or radiobiology is a science that studies the effect of ionizing and non-ionizing radiation on biological objects.
Taxonomy in biology is the science that classifies organisms based on their external similarity and relatedness.
Spongiology is the science of sponges.
Taxonomy is the study of the principles and practice of classification and systematization.
Theriology is a branch of zoology that studies mammals.
Toxicology is a science that studies poisonous (toxic) substances, the potential danger of their effects on organisms and ecosystems, mechanisms of toxic action, as well as diagnostic methods.
Phenology (from the Greek φαινόμενα - phenomena) is a system of knowledge and a set of information about seasonal natural phenomena, the timing of their occurrence and the reasons that determine these timings.
Physiology (from the Greek φύσις - nature and λόγος - knowledge) is the science of the essence of living things, life in normal conditions and in pathologies, that is, about the patterns of functioning and regulation of biological systems at different levels of organization.
Phytopathology (phyto-plant and pathology) is the science of plant diseases caused by pathogens (infectious diseases) and environmental factors (physiological factors).
Cytology (Greek κύτος “cell” and λόγος - “teaching”, “science”) is a branch of biology that studies living cells, their organelles, their structure, functioning, processes of cellular reproduction, aging and death.
Biological evolution (from Latin evolutio - “unfolding”) is a natural process of development of living nature, accompanied by changes in the genetic composition of populations and the formation of adaptations.
Embryology is the science that studies the development of the embryo: embryogenesis.
Endocrinology is the science of the structure and function of the endocrine glands (endocrine glands), the products they produce (hormones), the ways of their formation and effect on the body of animals and humans; as well as about diseases.
Entomology is a branch of zoology that studies insects.
Ethology is a field discipline of zoology that studies the genetically determined behavior (instincts) of animals, including humans.
Biological sciences and the aspects they study. Anatomy is the science of the internal structure of the body. Genetics is about heredity and variability. Embryology is the science of the embryonic development of an organism. Histology is the science of tissue structure. Cytology is the science of the structure of cell life. Morphology is the science of the external structure of an organism. Physiology is a science that studies life processes. Zoology is the science of animals. Botany is the science of plants. Microbiology is the science of bacteria and viruses.
Slide 7 from the presentation "Biology". The size of the archive with the presentation is 1990 KB.Biology 10th grade
summary of other presentations“Reproduction methods” - Reproduction by spores. Reproduction by division. Formation of germ cells. Types of asexual reproduction. Sporulation. Sexual reproduction. Individuals identical to the original organism. Asexual reproduction. Vegetative propagation. Reproduction. The ability to combine genetic material. The disappearance of sexual reproduction.
“Theories of the origin of living things” - My best lesson. Chemical evolution transition diagram. Nebula. The problem of nature. Theories of origin. Rules of judicial ethics. History of performances. Stages of the emergence of the solar system. Lesson structure. History of ideas about the origin of life. Group work in the lesson. The work of judges. Hypotheses about the origin of life. Matter. Lesson stage. Modern hypotheses. Debate. Game regulations. Additional question.
“Inorganic compounds of the cell” - Chemical elements of the cell. Chemical composition of the cell. Functions of water. Polarity of membranes of living cells. Included in water. Protein component. Composition of blood plasma. Exercise. Chemical substances. Note the properties of water. Highlight the characteristic properties. Properties of water. Macroelements. Substances. Dipole structure.
“Problems of the emergence of life on Earth” - The emergence of multicellular organisms. Conditions for the emergence of primitive living beings. History of carbon. Coacervate droplets. The emergence of primary organisms. Works by L. Pasteur. Theories of the origin of life. Development of life. History of ideas about the origin of life. The emergence of life on Earth. From carbon to proteins. Representations of ancient and medieval philosophers. Age of the Earth. Possibility of occurrence of complex organic compounds.
“Population dynamics” - A single-celled amoeba divides into two cells every three hours. Rare species. Dictionary. Survival curves. Mathematical and computer modeling. Malthus's Law. Population development models. Environmental strategy. Predator-prey model. Anthropogenic impact on growth types. Types of population growth. Graphs of changes in population numbers. Lesson plan. R-strategists. Population density. Which species have stable population dynamics.
“Viruses in the body” - Due to the high mutability of viruses, the treatment of viral diseases is quite difficult. Viral diseases. Structure and classification of viruses. Viruses are the causative agents of many dangerous diseases of humans, animals and plants. Viruses are hereditary. The first mention of smallpox in Russia dates back to the 4th century. Attempts to use viruses for the benefit of humanity are quite few. Like other organisms, viruses are capable of reproduction.
The first major biological science is botany. She studies plants. Botany is divided into many disciplines that can also be considered biological. Algology. Plant anatomy studies the structure of plant tissues and cells, as well as the laws by which these tissues develop. Bryology studies bryophytes, dendrology studies woody plants. Carpology studies the seeds and fruits of plants.
Lichenology is the science of lichens. Mycology is about mushrooms, mycogeorgaphy is about their distribution. Paleobotany is a branch of botany that studies the fossil remains of plants. Palynology studies pollen grains and plant spores. The science of plant taxonomy deals with their classification. Phytopathology studies various plant diseases caused by pathogenic and environmental factors. Floristry studies flora, a collection of plants historically formed in a certain territory.
The science of ethnobotany studies the interactions between people and plants. Geobotany is the science of the Earth’s vegetation, of plant communities – phytocenoses. The geography of plants studies the patterns of their distribution. Plant morphology is the science of patterns. Plant physiology is about the functional activity of plant organisms.
Zoology and microbiology
Ichthyology is the science of fish, carcinology is of crustaceans, ketology is of cetaceans, conchiology is of mollusks, myrmecology is of ants, nematology is of roundworms, oology is of animal eggs, ornithology is of birds. Paleozoology studies the fossil remains of animals, planktology studies plankton, primatology studies primates, theriology studies mammals and insects, protozoology studies unicellular organisms. Ethology deals with the study.
The third major branch of biology is microbiology. This science studies living organisms invisible to the naked eye: bacteria, archaea, microscopic fungi and algae, viruses. Sections are distinguished accordingly: virology, mycology, bacteriology, etc.
Biology is the science that studies living organisms. It reveals the laws of life and its development as a special natural phenomenon.
Among other sciences, biology is a fundamental discipline and belongs to the leading branches of natural science.
The term “biology” consists of two Greek words: “bios” - life, “logos” - teaching, science, concept.
It was first used to refer to the science of life in the early 19th century. This was done independently by J.-B. Lamarck and G. Treviranus, F. Burdach. At this time, biology was separated from the natural sciences.
Biology studies life in all its manifestations. The subject of biology is the structure, physiology, behavior, individual and historical development of organisms, their relationship with each other and the environment. Therefore, biology is a system, or complex, of sciences that are largely interconnected. Various biological sciences arose throughout the history of the development of science as a result of the isolation of various areas of study of living nature.
The major branches of biology include zoology, botany, microbiology, virology, etc. as sciences that study groups of living organisms that differ in key aspects of the structure and life activity. On the other hand, the study of the general patterns of living organisms led to the emergence of such sciences as genetics, cytology, molecular biology, embryology, etc. The study of the structure, functionality, behavior of living beings, their relationships and historical development gave rise to morphology, physiology, ethology, ecology, evolutionary teaching.
General biology studies the most universal properties, patterns of development and existence of living organisms and ecosystems.
Thus, biology is a system of sciences.
Rapid development in biology was observed in the second half of the 20th century. This was primarily due to discoveries in the field of molecular biology.
Despite its rich history, discoveries continue to be made in the biological sciences, discussions are ongoing, and many concepts are being revised.
In biology, special attention is paid to the cell (since it is the main structural and functional unit of living organisms), evolution (since life on Earth has undergone development), heredity and variability (underlying the continuity and adaptability of life).
There are a number of successive levels of life organization: molecular genetic, cellular, organismal, population-species, ecosystem. On each of them, life manifests itself in its own way, which is studied by the corresponding biological sciences.
The importance of biology for humans
For humans, biological knowledge primarily has the following meaning:
- Providing food for humanity.
- Ecological meaning - control of the environment so that it is suitable for normal life.
- Medical significance - increasing the duration and quality of life, fighting infections and hereditary diseases, developing drugs.
- Aesthetic, psychological significance.
Man can be considered as one of the results of the development of life on Earth. People's lives are still strongly dependent on general biological mechanisms of life. In addition, man influences nature and experiences its impact himself.
Human activities (development of industry and agriculture), population growth have caused environmental problems on the planet. The environment is polluted and natural communities are destroyed.
To solve environmental problems, it is necessary to understand biological laws.
In addition, many branches of biology are important for human health (medical significance). People's health depends on heredity, living environment and lifestyle. From this point of view, the most important sections of biology are heredity and variability, individual development, ecology, and the doctrine of the biosphere and noosphere.
Biology solves the problem of providing people with food and medicine. Biological knowledge underlies the development of agriculture.
Thus, a high level of development of biology is a necessary condition for the well-being of humanity.