Asexual reproduction. Budding What does budding mean reproduction

30.10.2019

Reproduction is the ability of all organisms to reproduce their own kind, which ensures the continuity and acceptability of life. The main methods of reproduction are presented:

Asexual reproduction is based on cell division by mitosis, in which two equivalent daughter cells (two organisms) are created from each mother cell (organism). The biological role of asexual reproduction is the emergence of organisms that are identical to the parent in terms of the content of hereditary material, as well as anatomical and physiological properties (biological copies).

There are the following methods of asexual reproduction Key words: fission, budding, fragmentation, polyembryony, sporulation, vegetative reproduction.

Division- a method of asexual reproduction, characteristic of unicellular organisms, in which the mother individual is divided into two or more daughter cells. We can distinguish: a) simple binary fission (prokaryotes), b) mitotic binary fission (protozoa, unicellular algae), c) multiple fission, or schizogony (malarial plasmodium, trypanosomes). During the division of paramecium (1), the micronucleus is divided by mitosis, the macronucleus by amitosis. During schizogony (2), the nucleus first divides repeatedly by mitosis, then each of the daughter nuclei is surrounded by cytoplasm, and several independent organisms are formed.

budding- a method of asexual reproduction, in which new individuals are formed in the form of outgrowths on the body of the parent individual (3). Daughter individuals can separate from the mother and move on to an independent lifestyle (hydra, yeast), they can remain attached to it, forming colonies in this case (coral polyps).

Fragmentation(4) - a method of asexual reproduction, in which new individuals are formed from fragments (parts) into which the parent individual breaks up (annelids, starfish, spirogyra, elodea). Fragmentation is based on the ability of organisms to regenerate.

Polyembryony- a method of asexual reproduction, in which new individuals are formed from fragments (parts) into which the embryo breaks up (monozygous twins).

Vegetative propagation- a method of asexual reproduction, in which new individuals are formed either from parts of the vegetative body of the mother individual, or from special structures (rhizome, tuber, etc.) specially designed for this form of reproduction. Vegetative propagation is characteristic of many groups of plants, it is used in horticulture, horticulture, plant breeding (artificial vegetative propagation).

sporulation(6) - reproduction through spores. controversy- specialized cells, in most species are formed in special organs - sporangia. In higher plants, spore formation is preceded by meiosis.

Cloning- a set of methods used by humans to obtain genetically identical copies of cells or individuals. Clone- a set of cells or individuals descended from a common ancestor through asexual reproduction. Cloning is based on mitosis (in bacteria, simple division).

During sexual reproduction in prokaryotes, two cells exchange hereditary information as a result of the transfer of a DNA molecule from one cell to another along the cytoplasmic bridge.

budding, one of the methods of asexual (vegetative) reproduction of animals and plants. P. is carried out by the formation of a kidney on the maternal organism - an outgrowth, from which a new individual develops. From plants, certain marsupial fungi are capable of P. (for example, yeast, for to-rykh P. - main. method of reproduction), a number of basidiomycetes, as well as liverwort mosses (the so-called brood buds reproduce). Among P.'s animals, protozoa (some flagellates, ciliates, sporozoa), sponges, coelenterates, some worms, bryozoans, pterygobranchs, and tunicates reproduce. In animals, P. is external and internal; the first is divided into parietal, with Krom the kidneys are formed on the mother's body, and stolonial P., when the kidneys are formed on the special. outgrowths - stolons (some coelenterates and tunicates). With internal The item the new individual develops from the isolated vnutr. part of the mother's body; such are the gemmules of sponges and the statoblasts of bryozoans, which have protective membranes and serve as preim. for experiencing in winter or arid conditions when the mother's body dies. In a number of animals, P. does not reach the end; young individuals remain connected with the mother's organism; as a result, colonies appear, consisting of many individuals (see. colonial organisms). Sometimes P. can be caused artificially by various effects on the mother's body, for example, burns or cuts. A. V. Ivanov

Living organisms occurs with the participation of only one cell without the formation gametes. In this case, new organisms are formed in some species in special organs, while in others - from one or more cells of the mother's organism. There are such types of asexual reproduction: vegetative reproduction, sporulation, polyembryony, fragmentation, budding and division.

Vegetative propagation- this is a type of asexual reproduction, in which the reproduction of the cells of a new organism occurs from special structures of the maternal organism (tubers, rhizomes, etc.) or from a part of the vegetative body of the maternal individual. This type of reproduction is often found among plants.

Vegetative reproduction in examples.

Type of vegetative organ	Method of vegetative propagation	Examples in the plant world
	leaf cuttings	coleus, gloxinia, begonia
Corm	tuberous	Crocus, gladiolus
	Root offspring	Cherry, thistle, plum, lilac, thistle
	root cuttings	Raspberry, aspen, willow, wild rose, dandelion
Underground parts of shoots	Bulb	Tulip, onion, garlic, hyacinth
		Jerusalem artichoke, potatoes, weekday
	Rhizome	Bamboo, iris, asparagus, lily of the valley
Aerial parts of shoots	stem cuttings	Currant, grape, gooseberry
	The division of the bushes	Daisy, rhubarb, primrose, phlox
		Grapes, bird cherry, gooseberries

sporulation is reproduction by means of spores. Spores are cells that usually form in sporangia, specialized organs. In higher organisms, before the formation of pores, meiosis.

Polyembryony(schizogony) is a type of asexual reproduction in which a new generation develops from parts into which the embryo breaks up (monozygous twins).

Fragmentation is a type of asexual reproduction in which daughter organisms are formed from parts into which the mother organism breaks up. In this way, elodea, spirogyra, starfish, annelids breed.

budding- This is a type of asexual reproduction in which daughter organisms are formed in the form of processes on the mother's organism. When budding, a new organism can separate from the parent and live separately (for example, hydra), or it can remain attached to the parent organism. The latter type of budding is common in coral colonies.

Division- This is the simplest method of asexual reproduction, in which the mother organism is divided into two or more daughter organisms. This method is typical for many unicellular organisms.

Reproduction is the process of reproduction of living organisms. There are two types of reproduction - sexual (fusion of gametes) and asexual (development from a somatic cell). Several types of asexual reproduction are characteristic of unicellular and multicellular organisms - plants and animals.

Definition

Asexual reproduction is the reproduction of offspring with the participation of one asexual (having no gamete) organism. The new organism receives all genetic information from one parent, therefore, in the absence of mutations, it becomes its copy.

Features of asexual reproduction are:

formation and development of a unicellular or multicellular organism through mitosis;
absence of meiosis;
rapid increase in the number of offspring.

Asexual reproduction is characteristic of all unicellular organisms, fungi, primitive multicellular animals, and many types of plants. This method of reproduction of offspring appeared much earlier than sexual reproduction. Conditionally transitional forms from asexual to sexual reproduction are:

parthenogenesis - development of an individual from the maternal gamete;
hermaphroditism - the presence of signs of both sexes in one organism.

Rice. 1. Hermaphroditism in snails.

Kinds

There are several ways to reproduce asexually. Features are described in the table “Types of asexual reproduction”.

Cloning

The phenomenon in which a person artificially receives a living organism asexually is called cloning. Rarely found in nature. One example of natural cloning is identical or homozygous twins. However, they are identical only to each other and differ from their parents.

The method of reproducing identical offspring from a parent cell is applicable even to those organisms that naturally reproduce sexually. A textbook example is Dolly the sheep. Cloning was carried out by transferring the nucleus of the somatic cell of the parent with all the genetic information into the egg of the donor.

Rice. 3. Dolly the sheep.

In fact, any method of asexual reproduction is a kind of cloning, because. a somatic rather than a germ cell is used for reproduction, and the offspring are identical to the parent.

What have we learned?

Asexual reproduction is characteristic of unicellular and multicellular organisms. Genetic diversity does not occur because the resulting offspring develop from somatic cells and are completely identical to the parent's body. There are five modes of asexual reproduction - fission, spore formation, budding, fragmentation, and vegetative reproduction. Cloning is an artificial method of asexual reproduction.

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reproduction- the property of living organisms to reproduce their own kind. There are two main breeding method- asexual and sexual.

Asexual reproduction is carried out with the participation of only one parent and occurs without the formation of gametes. The daughter generation in some species arises from one or a group of cells of the parent organism, in other species - in specialized organs. There are the following methods of asexual reproduction: fission, budding, fragmentation, polyembryony, spore formation, vegetative reproduction.

Polyembryony- a method of asexual reproduction, in which new individuals are formed from fragments (parts) into which the embryo breaks up (monozygous twins).

Vegetative organ	Method of vegetative propagation	Examples
Root	root cuttings	Rosehip, raspberry, aspen, willow, dandelion
Root	Root offspring	Cherry, plum, thistle, thistle, lilac
Aerial parts of shoots	The division of the bushes	Phlox, daisy, primrose, rhubarb
	stem cuttings	Grapes, currants, gooseberries
	layering	Gooseberries, grapes, bird cherry
Underground parts of shoots	Rhizome	Asparagus, bamboo, iris, lily of the valley
	Tuber	Potato, weekday, Jerusalem artichoke
	Bulb	Onion, garlic, tulip, hyacinth
	Corm	Gladiolus, crocus
Sheet	leaf cuttings	Begonia, Gloxinia, Coleus

Sexual reproduction is carried out with the participation of two parent individuals (male and female), in which specialized cells are formed in special organs - gametes. The process of formation of gametes is called gametogenesis, the main stage of gametogenesis is meiosis. The daughter generation develops from zygotes- a cell formed as a result of the fusion of male and female gametes. The process of fusion of male and female gametes is called fertilization. An obligatory consequence of sexual reproduction is the recombination of genetic material in the daughter generation.

Depending on the structural features of gametes, the following can be distinguished forms of sexual reproduction: isogamy, heterogamy and ovogamy.

isogamy(1) - a form of sexual reproduction in which gametes (conditionally female and conditionally male) are mobile and have the same morphology and size.

Heterogamy(2) - a form of sexual reproduction in which female and male gametes are mobile, but female are larger than male and less mobile.

Ovogamy(3) - a form of sexual reproduction in which the female gametes are immobile and larger than the male gametes. In this case, the female gametes are called eggs, male gametes, if they have flagella, - spermatozoa if they don't have - sperm.

Ovogamy is characteristic of most animal and plant species. Isogamy and heterogamy are found in some primitive organisms (algae). In addition to the above, some algae and fungi have forms of reproduction in which germ cells are not formed: chologamy and conjugation. At chologamy unicellular haploid organisms merge with each other, which in this case act as gametes. The resulting diploid zygote then divides by meiosis to form four haploid organisms. At conjugations(4) the contents of individual haploid cells of the filamentous thalli are fused. Through specially formed channels, the contents of one cell flows into another, a diploid zygote is formed, which usually also divides by meiosis after a dormant period.

Go to lectures №13"Methods of division of eukaryotic cells: mitosis, meiosis, amitosis"

Go to lectures №15"Sexual reproduction in angiosperms"

*View*	*Peculiarities*	*Examples*
	Formation of daughter cells from one parent cell. Division can be single (into two parts) or multiple (more than 1000 daughter cells)	Amoeba, chlamydomonas, chlorella, bacteria
sporulation	The release of spores from special organs - sporangia. Spores have a protective shell, which is destroyed under favorable conditions for development.	Mushrooms, ferns, mosses, algae
budding	Creation of offspring from the tissues of the parent body by protrusion and separation
Fragmentation	The formation of a new organism from separate segments or parts of the parent	Tapeworms, algae, coelenterates
Vegetative propagation	Natural or artificial cultivation of new individuals from the vegetative organs of plants	Geranium, violet, begonia