Reproduction is a property of organisms. Cell division as the basis for growth, development and reproduction of organisms


Reproduction e – the property of living organisms to reproduce their own kind.
Cell cycle- the life of a cell from the moment of its appearance in the process of division of the mother cell until its own division, including this division, or its death.
Mitosis- the process of indirect division of somatic cells of eukaryotes, in which hereditary material first doubles and then is evenly distributed between daughter cells.
Amitosis- direct cell division, in which DNA is not evenly distributed between daughter cells.

2. Why is reproduction considered one of the most important stages in the individual development of organisms?
The cells of a living being cannot divide indefinitely, otherwise the organism would be immortal. At a certain period, death programs are launched in cells. To leave offspring, to pass on your genetic information In order for a species not to disappear, the organism must reproduce.

3. Consider the mitotic cycle of a human somatic cell shown in the figure and fill in the table.

Mitotic cycle of a somatic cell

4. Name the periods of the mitotic cycle of the cell, indicated in the figure above by letters A and B, and characterize biological significance each of them.
A – interphase. The period of preparation for division. As a result, energy is accumulated for mitosis and microtubule proteins are synthesized for the spindle. By the end of interphase, each chromosome consists of two chromatids. This is necessary for further cell division and uniform transfer of genetic material between daughter cells.
B – mitosis. As a result, from one mother cell two daughter cells are formed with the same set of chromosomes, identical to the mother cell. Thus, new cells are reproduced with quantitatively and qualitatively new genetic information. Mitosis is necessary for the normal development and growth of a multicellular organism.

5. Fill out the table.

Phases of mitosis

6. What is apoptosis? What is its biological significance?
Apoptosis is “programmed” cell death. It is necessary for the body to gradually age and eventually die. The organism should not be immortal, new descendant organisms should appear, and the species should evolve.

7. What happens in the body as a result of disruption of apoptosis processes?
As a result of weakened apoptosis, autoimmune diseases and malignant tumors occur. With increased apoptosis, degenerative processes and deformities with tissue defects occur.

8. Which cells are characterized by amitosis? Give examples.
During amitosis, there is no uniform distribution of DNA between daughter cells. Sometimes cytokinesis does not occur and a binucleate cell is formed. Amitosis is characteristic of cells of dying tissues and malignant tumors.

Asexual reproduction


Asexual reproduction- a form of reproduction in which a unicellular organism or cells of a multicellular organism divide and the formation of daughter individuals occurs.
Vegetative propagation- a type of asexual reproduction of a multicellular organism, in which offspring develop from a group of parent cells.

2. What is biological role asexual reproduction?
Asexual reproduction allows a rapid increase in the number of this species under favorable conditions. However, such reproduction does not increase the genetic diversity of the species.

3. Make a diagram.


Sexual reproduction. Meiosis

1. Give definitions of concepts.
Sexual reproduction- a form of reproduction in which individuals of each next generation arise as a result of the fusion of two specialized haploid cells - gametes.
Sexual process- the process of fusion of sex cells (gametes), as a result of which a zygote appears.
Meiosis– division of the nucleus of a eukaryotic cell with a halving of the number of chromosomes.
Gametes– reproductive cells that have a haploid set of chromosomes and participate in sexual reproduction.

2. What is the biological role of sexual reproduction?
During sexual reproduction, the genetic diversity of the species increases. Descendants get the opportunity to adapt to constantly changing conditions environment, and other new features.

3. Fill out the table.

Phases of meiosis

4. Complete the diagram.

Changes in the chromosome set of cells (n) and the number of DNA molecules (c) during meiosis


5. What methods of sexual reproduction do you know?
Conjugation- a form of sexual process in which the fusion of two physiologically equivalent cells occurs. It is observed in some unicellular organisms.
Copulation– sexual process, the fusion of two sex cells (gametes); the union of two individuals during sexual intercourse.
Isogamy- a type of sexual reproduction in which female and male gametes are indistinguishable from each other.
Heterogamy- a type of sexual reproduction in which female gametes are large and immobile (eggs), and male gametes are small and mobile (sperm).

6. Look at Fig. in the textbook. 51 on p. 123. Fill out the table.

Formation of germ cells (gametogenesis)

7. Describe the biological essence of gametogenesis.
Gametogenesis is the process of formation of germ cells: from one diploid cell 4 haploid ones are formed. Sex cells must have a haploid set so that during subsequent sexual reproduction of the organism, its descendants retain a constant set of chromosomes (genotype).

8. Look at the drawing. Determine which pictures correspond to mitosis and which to meiosis. Explain how you differentiated these processes. Distribute the digital designations (1-12) in accordance with the belonging of the depicted phases to the types of cell division, in the sequence of their occurrence.
Figures 2, 5, 7, 8 show mitosis. Here we see 4 stages, from the beginning of the formation of chromosomes with two chromatids, to the formation of two cells with despiralized chromosomes. All chromosomes of one cell are the same color.
Figures 1, 3, 4, 6, 9,10, 11, 12 show meiosis. Here we can see two divisions, at the very end 4 haploid cells are formed. Chromosomes are shown with sections of different colors, since in a diploid cell there are male and female chromosomes, then conjugation and crossing over occur between them.
Mitosis: 8, 2, 5, 7.
Meiosis: 4, 6, 1, 3, 9, 11, 10, 12.

Fertilization and its meaning

1. Define the concepts.
Fertilization- process of gamete fusion.
Zygote- the first cell of a new organism formed as a result of fertilization.
Double fertilization- a sexual process in angiosperms in which both the egg and the central cell of the embryo sac are fertilized by two sperm.

2. What is the biological role of fertilization?
During fertilization, the sperm fuses with the egg. Only as a result of this process does a zygote arise, containing the genetic material of both parents.

3. How is external fertilization different from internal?
External fertilization occurs outside the female's body, usually in aquatic environment(fish, shellfish, amphibians).
During internal fertilization, the “meeting” of the sperm and egg occurs in the reproductive tract of the female (terrestrial animals).

4. What is the essence of double fertilization in flowering plants?
The essence of double fertilization is the formation of a diploid zygote (1 sperm and an egg), from which the seed embryo then develops, and the fusion of the second sperm with the central diploid cell, resulting in the formation of a triploid cell. From the triploid cell, the endosperm develops in the future, in which nutrients are stored.

Reproduction is the reproduction by an organism of similar organisms. Thanks to him, continuity of life is ensured. There are two ways to form new organisms: asexual and sexual reproduction. Asexuality, in which only one organism participates, occurs through cell division in half, sporulation, budding, or vegetatively. It is characteristic mainly of primitive organisms. In asexual reproduction, the new organisms are a copy of the parent. Sexual reproduction occurs with the help of sex cells called gametes. It mainly involves two organisms, which contributes to the emergence of new individuals that differ from the parent ones. Many animals are characterized by alternating asexual and sexual reproduction.

Types of sexual reproduction

There are the following types of sexual reproduction:

  • bisexual;
  • hermaphrodite;
  • parthenogenesis, or virgin reproduction.

Dioecious reproduction

Dioecious reproduction is characterized by the fusion of haploid gametes, which is called fertilization. Fertilization results in a diploid zygote containing genetic information from both parents. Dioecious reproduction is characterized by the presence of the sexual process.

Types of sexual process

There are three types of sexual process:

  1. Isogamy. It is characterized by the fact that all gametes are mobile and have the same size.
  2. Anisogamy or heterogamy. Gametes have different sizes; there are macrogametes and microgametes. But both gametes are capable of movement.
  3. Oogamy. It is characterized by the presence of a large immobile egg and a small sperm capable of movement.

Hermaphroditism

Parthenogenesis

Some organisms are able to develop from an unfertilized cell. This sexual reproduction is called parthenogenesis. With its help, ants, bees, wasps, aphids and some plants reproduce. A type of parthenogenesis is pedogenesis. It is characterized by virgin reproduction of larvae. Some dipterans and beetles reproduce using pedogenesis. Parthenogenesis ensures a rapid increase in population size.

Plant propagation

Plants, like animals, can reproduce asexually and sexually. The difference is that sexual reproduction in angiosperms occurs through double fertilization. What is it? In double fertilization, discovered by S.G. Navashin, two sperm take part in the fertilization of the egg. One of them unites with the egg. This produces a diploid zygote. The second sperm fuses with the diploid central cell to form a triploid endosperm containing a supply of nutrients.

Biological meaning of sexual reproduction

Sexual reproduction makes organisms resistant to changes and unfavorable conditions environment, increases their viability. This is facilitated by the diversity of offspring born as a result of the combination of heredity of two organisms.

Reproduction, the inherent property of all organisms to reproduce their own kind, ensuring the continuity and continuity of life. All forms of R. are based on organisms that have cellular structure, lies cell division. Various classifications of forms of R. have been proposed. There are three main methods of R.: asexual, vegetative and sexual. In asexual R., the organism develops from a single cell that is not differentiated sexually. In vegetative R., the beginning of a new organism is given by multicellular rudiments, sometimes complexly differentiated. Sexual R. is preceded by education gametes (sex cells); R. itself comes down to their merger into zygote - fertilization, accompanied by the union of not only the cytoplasm of the gametes, but also their nuclei. The beginning of the R. period in some cases coincides with the cessation of growth, in others it does not entail a stop in the growth of the individual and stops only with the onset of old age or continues until the death of the organism, in others it begins several years after the cessation of growth. R. can be single or multiple. For unicellular organisms that reproduce by division, as well as for annual and biennial flowering plants, R. is at the same time the completion of their life cycle. Some (so-called monocarpic) perennial plants, as well as a few species of fish, reproduce once in their life.

Much more often in the plant and animal world, multiple reactions are observed. Each species is characterized by a certain intensity of radiation, sometimes varying within quite a wide range depending on the conditions of existence.

The onset of the R. period and its intensity are greatly influenced by environmental conditions - temperature, length daylight hours, lighting intensity, food, etc. In higher animals, the activity of the reproductive organs is associated with the functions of the endocrine glands, which makes it possible to stimulate or delay puberty. For example, in fish, an additional transplantation of the pituitary gland or the introduction of its hormones causes the onset of maturity, which is used in the practice of breeding valuable fish, such as sturgeon.

Lit.: Myasoedov S.V., Phenomena of reproduction and sex in organic world, Tomsk, 1935; Hartman M., General biology, translation (translation) from German (German), M. - L., 1936; Dogel V. A., Polyansky and Yu. I., Kheisin E. M., General protozoology, M. - L., 1962; Willy K. and Dethier V., Biology. (Biological processes and laws), translated (translation) from English (English), M., 1974; Meisenheimer J., Geschlecht und Geschlechter im Tierreiche, Jena, 1921; Hartmann M., Die Sexualität, Stutt., 1956.

Yu. I. Polyansky.

Lit.: Meyer K.I., Plant propagation, M., 1937; Kursanov L.I., Mycology, 2nd ed., M., 1940; Mageshwari P., Embryology of Angiosperms, translation (translation) from English (English), M., 1954; Poddubnaya-Arnoldi V. A., General embryology of angiosperms, M., 1964; Botany, 7th ed., vol. 1, M., 1966; Schnarf K., Embryologie der Angiospermen, B 1 B., 1927; his, Embryologie der Gymnospermen, B., 1933; Chamberlain Chi. J., Gymnosperms. Structure and evolution, Chi., .

D. A. Trankovsky.

Between individuals - sexual process.

Asexual reproduction is the oldest and most in a simple way reproduction and is widespread in unicellular organisms (bacteria, blue-green algae, chlorella, amoebas, ciliates). This method has its advantages: there is no need to find a partner, and beneficial hereditary changes are preserved almost forever. However, with this method of reproduction, the variability necessary for natural selection is achieved only through random mutations and therefore occurs very slowly. However, it should be noted that the ability of a species to reproduce asexually does not exclude the ability to undergo the sexual process, but then these events are separated in time.

The most common method of reproduction of single-celled organisms is by dividing into two parts, forming two separate individuals.

Alternation of generations in plants

The gametophyte develops from a spore, has a single set of chromosomes and has sexual reproductive organs - gametangia. In heterogametic organisms, male gametangia, that is, producing male gametes, are called antheridia, and female gametangia are called archegonia. Since the gametophyte, like the gametes it produces, has a single set of chromosomes, gametes are formed by simple mitotic division.

When gametes fuse, a zygote is formed, from which a sporophyte develops. The sporophyte has a double set of chromosomes and carries organs of asexual reproduction - sporangia. In heterosporous organisms, male gametophytes develop from microspores, bearing exclusively antheridia, and from megaspores, female gametophytes develop. Microspores develop in microsporangia, megaspores develop in megasporangia. During sporulation, meiotic reduction of the genome occurs, and a single set of chromosomes characteristic of the gametophyte is restored in the spores.

Evolution of reproduction

The evolution of reproduction, as a rule, went in the direction from asexual forms to sexual ones, from isogamy to anisogamy, from the participation of all cells in reproduction to the division of cells into somatic and sexual ones, from external fertilization to internal fertilization with intrauterine development and care for the offspring.

The rate of reproduction, the number of offspring, the frequency of generational changes, along with other factors, determine the rate of adaptation of the species to environmental conditions. For example, high rates reproduction and frequent changes of generations allow insects to short term develop resistance to pesticides. In the evolution of vertebrates - from fish to warm-blooded animals - there is a tendency towards a decrease in the number of offspring and an increase in their survival.

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See what “Reproduction” is in other dictionaries:

    REPRODUCTION- the property of reproducing their own kind inherent in all organisms, ensuring the continuity and continuity of life. R.'s methods are extremely varied. Usually there are three main ones. forms of R.: asexual (in protozoa, division into two, schizogony, in higher... ... Biological encyclopedic dictionary

    REPRODUCTION- REPRODUCTION, reproduction, plural. no, cf. 1. Action under Ch. multiply multiply and state according to ch. multiply multiply. 2. The process of producing offspring (biol.). Sexual reproduction. Asexual reproduction. Reproduction by division. Reproduction... ... Dictionary Ushakova

    reproduction- Cm … Synonym dictionary

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    Reproduction- the ability of organisms to produce their own kind, which ensures the preservation of their species and the continuity of stay in biocenoses. Reproduction is distinguished by asexual reproduction, by dividing individuals (for example, in unicellular plants), vegetative development... ... Ecological dictionary

    REPRODUCTION- REPRODUCTION, or the ability of self-reproduction, is one of the main characteristics of living things, ensuring the preservation of the life of the species. Among the seemingly endless variety of methods of R., two main types can be outlined: R. using one cell, or... ... Great Medical Encyclopedia

    reproduction- REPRODUCTION, reproduction REPRODUCE/MULTIPLY, reproduce, breed/divorce, obsolete. kept, outdated multiply, expand to be fruitful/to multiply and multiply... Dictionary-thesaurus of synonyms of Russian speech

    Reproduction- * reproduction * reproduction is the ability of the body to produce its own kind, which ensures the preservation of life. R. is divided into: a) asexual, or vegetative, excluding meiosis (see); b) fertilization occurs by separating parts... ... Genetics. encyclopedic Dictionary

Introduction........................................................ ........................................................ ....... 3

1. Types of reproduction.................................................. ........................................ 4

1.1 Asexual reproduction............................................................ ............................ 4

1.2 Sexual reproduction................................................................. ........................... 6

2. Individual development of organisms.................................................. ....... 12

2.1 Embryonic period of development.................................................... ......... 12

2.2 Postembryonic period of development.................................................... .. 16

2.3 General patterns development. Biogenetic law................... 18

Conclusion................................................. ........................................................ .21

Bibliography................................................ ..................................... 22


Introduction

The ability to reproduce, i.e. producing a new generation of individuals of the same species is one of the main characteristics of living organisms. During the process of reproduction, genetic material is transferred from the parent generation to the next generation, which ensures the reproduction of characteristics not only of a given species, but of specific parent individuals. For a species, the meaning of reproduction is to replace those of its representatives who die, which ensures the continuity of the existence of the species; in addition, under suitable conditions, reproduction makes it possible to increase the total number of the species.

Each new individual, before reaching the stage at which it is capable of reproduction, must go through a number of stages of growth and development. Some individuals die before reaching reproductive stage(or sexual maturity) as a result of destruction by predators, diseases and various kinds random events; therefore, the species can survive only on the condition that each generation produces more offspring than there were parent individuals who took part in reproduction. Population sizes fluctuate depending on the balance between reproduction and extinction of individuals. There are a number of different propagation strategies, each with distinct advantages and disadvantages; all of them will be described in this abstract.


1. Types of reproduction

Known various shapes reproduction, but all of them can be combined into two types: sexual and asexual.

Sexual reproduction refers to the change of generations and the development of organisms from specialized – sex – cells, which are formed in the gonads. In this case, a new organism develops as a result of the fusion of two germ cells formed by different parents. However, in invertebrate animals, sperm and eggs are often formed in the body of one organism. This phenomenon - bisexuality - is called hermaphroditism. Flowering plants are also bisexual. In most species of angiosperms (flowering) plants, a bisexual flower includes both stamens, which form male reproductive cells - sperm, and pistils, which contain eggs. In approximately a quarter of the species, male (staminate) and female (pistillate) flowers develop independently, i.e. their flowers are unisexual. An example is hemp. In some plants - corn, birch - both male and female flowers appear on the same individual.

Some species of animals and plants develop
unfertilized egg. This type of reproduction is called virgin or parthenogenetic.

Asexual reproduction is characterized by the fact that a new individual develops from non-sexual, somatic (bodily) cells.

1.1 Asexual reproduction

With asexual reproduction, a new organism can arise from a single cell or from several asexual (somatic) cells of the mother. Asexual reproduction involves only one parent. Since the cells that give rise to daughter organisms arise as a result of mitosis, all descendants will be similar in hereditary characteristics to the maternal individual.

Rice. 1. Reproduction of green euglena

Many protozoa (amoeba, green euglena, etc.), unicellular algae (Chlamydomonas) reproduce by mitotic cell division (Fig. 1). Other unicellular organisms - some lower fungi, algae (chlorella), animals, for example the causative agent of malaria - plasmodium falciparum, are characterized by sporulation. In this case, the cell disintegrates into big number individuals, equal to the number of nuclei previously formed in the parent cell as a result of repeated division of its nucleus. Multicellular organisms are also capable of sporulation: these are mosses, higher fungi, multicellular algae, pteridophytes and some others.

In both unicellular and multicellular organisms, budding is also a method of asexual reproduction. For example, in yeast fungi and some ciliates (sucking ciliates), when budding on the mother cell, a small tubercle containing a nucleus is initially formed - a bud. It grows, reaches a size close to the size of the mother's body, and then separates, moving on to independent existence. In multicellular organisms (freshwater hydra), the kidney consists of a group of cells from both layers of the body wall. The bud grows, lengthens, and a mouth opening appears at its anterior end, surrounded by tentacles. Budding ends with the formation of a small hydra, which then separates from the mother organism.

In multicellular animals asexual reproduction carried out in the same way (jellyfish, annelids, flatworms, echinoderms). From each such part a full-fledged individual develops.

Vegetative propagation is widespread in plants, i.e. body parts - cuttings, tendrils, tubers. Thus, potatoes reproduce by modified underground parts of the stem - tubers. Jasmine and willow shoots - cuttings - take root easily. Grapes, currants, and gooseberries are propagated using cuttings.

Long creeping stems of strawberries - tendrils - form buds, which, taking root, give rise to a new plant. Few plants, such as begonia, can be propagated by leaf cuttings (leaf blade and petiole). On the underside of the leaf, in places where large veins branch, roots appear, on the top - buds, and then shoots.

The root is also used for vegetative propagation. In gardening, raspberries, cherries, plums, and roses are propagated using cuttings from lateral roots. Dahlias reproduce using root tubers. Modification of the underground part of the stem - the rhizome - also forms new plants. For example, sow thistle with the help of rhizomes can produce more than a thousand new individuals per 1 m2 of soil.


... (the presence of proteins, carbohydrates, lipids, mineral salts, vitamins, microelements in the feed). Oxygen, temperature, light (synthesis of vitamin D) are also important. Growth and individual development animal organisms are subject to neurohumoral regulation by humoral and nervous regulatory mechanisms. Hormone-like active substances called phytohormones have been discovered in plants. Latest...

Foraminifera) division occurs into larger number cells. In all cases, the resulting cells are completely identical to the original one. The extreme simplicity of this method of reproduction, associated with the relative simplicity of the organization of single-celled organisms, allows reproduction very quickly. Thus, under favorable conditions, the number of bacteria can double every 30–60 minutes. Reproducing asexually...

In the YuUNIIPOK nursery it is used to propagate most varieties of honeysuckle and this method gives good and satisfactory results. For the propagation of edible honeysuckle by green and lignified cuttings, elite planting material grown in the YuUNIPOK is used, as well as with the inclusion of zoned and recommended for breeding purposes and production testing varieties from...

Where they merge with the egg. The archegonium is most well developed in mosses. Subsequently, its reduction is observed.Chapter II.