Types of sexual reproduction and sexual reproduction definition | types of sexual reproduction | types of sexual reproduction in plants, bacteria, fungi and animals.
Reproduction make continuity of life in organisms from one generation to next generation. Sexual reproduction play major roles in producing new offspring in some bacteria, fungi, algae, lower plants like bryophytes, pteridophytes, gymnosperm and higher plant angiosperm and in various animals category such as amphibian, fishes, reptiles and mammals including human beings
In this topic we know about types of sexual reproduction in bacteria, plants, fungi and animals and definition of sexual reproduction.
Table of Contents
What is sexual reproduction definition
Sexual reproduction is that type of reproduction involving the fusion of haploid female gamete (ovum) and haploid male gamete (sperm), resulting the formation of diploid zygote that later develop into new organism which is genetically distinct from parents.
All organisms have to reach a certain stage of growth and maturity in their life before they can reproduce sexually. This period of growth is known as Juvenile phase and also it is called as vegetative phase in plants and reproductive phase start after the end of Juvenile phase or vegetative phase
Important features and characteristics of sexual reproduction
1) in sexual reproduction generally involvement of two parents male and female so it is called as biparental reproduction except some organism
2) it involves formation and fusion of two haploid male and female gametes such as fusion of ovum and sperm in animal case and fusion of pollen grains and egg cell in plant case
3) sex cell like a sperm (spermatogenesis) and ova (oogenesis) is formed by the process of meiosis during the gametogenesis in animals and in plant microsporogenesis forms pollen grains and megasporogenesis forms egg cell and polar nuclei
4) sexual reproduction also known as germinal reproduction because of new organisms reproduce from germinal cells of parents
5) offspring which are produce in sexual reproduction have genetically different from parents so variation apear due to new combination of gene during crossing over so it play important role in evolution
6) sexual reproduction in slow multiplication
7) unit of reproduction in sexual reproduction is haploid gametes
8) sexual reproduction is found in higher plants and animal
Sexuality in organism
Sexuality in organism means presence of sex cells in body of organism they represent either it may be male, female or both. Plant may be bisexual (presence of both male and female) or unisexual ( presence of single sex cell). Animal also be bisexual or unisexual as plant. Now several sexuality in organism defined in plants and animals are as follows:-
1) bisexual flower :- the flower which have both the essential organ like androecium and gynoecium is known as perfect or bisexual or hermaphrodite
2) unisexual flower :- if any of two reproductive organ androecium and gynoecium is missing in flower is known as imperfect or unisexual flower
3) staminate flower :- unisexual flowers if carpel are absent it is termed as male flower or staminate flower
4) pistilate flower :- unisexual flower if stamen are absent it is term as female flower or pistillate flower
5) neuter flower :- if both essential whorls of flower is absent that is termed as neuter flower
6) homothallic :- in several fungi and algae homothallic term is used to denote bisexual condition
7) heterothallic :- unisexual condition in fungi and algae is term as heterothallic condition
8) monoecious :- a plant may have both male and female flowers are termed as monoecious for example maize and castor
9) dioecious :- when male and female flowers are present on different plants this plant is known as dioecious. For example papaya, Mulberry, Data Palm
10) bisexual animal :- presence of both gonad female ovary and male gonads testis in same parent is known as bisexual animal. For example sponge, Taenia, fasciola, earthworm and leech, bisexual condition in animal is also known as hermaphrodite
11) unisexual animal :- presence of both gonads female and male gonads in different parents known as unisexual animal for example cockroach human beings
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Types of sexual reproduction
Two major types of sexual reproduction based on the nature of fusing structure are- 1) syngamy and 2) conjugation. syngamy refers to it complete and permanent fusion of two haploid male and female gametes to form a diploid zygote. It is the most common mode of sexual reproduction seen in higher plants and animals including human beings whereas conjugation refers to temporary union of two organism by cytoplasmic brige to exchange micronuclear material. This type of reproduction observed in single cell organism is called bacteria
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Syngamy in animals/ types of sexual reproduction in animals
Syngamy in animals generally refers to to permanent fusion of two haploid male and female gamete that resulting diploid zygote cells, letter on develop into new organism which is geneticaly distinct from parents.
In animals there are two types of haploid male and female gametes involved in syngamy are – 1) sperm and 2) ovum. Sperm is micro gamete, microscopic and motile gametes formed by spermatogenesis process in reproductive organ called testis in male gonad of animal whereas ovum is also called as macro- gamete is large a spherical and non motile and is formed by oogenesis in reproductive organ called ovary in female gonad.
Types of sexual reproduction in animals on the basis of source of fusing gametes syngamy is categorised into two types are- a) endogamy and b) exogamy. Endogamy involves fusion of two types of male and female gametes that derived from same gonad from single parent. For example:- Taenia and fasciola and it is also known as self fertilization whereas Exogamy refers to fusion of two haploid gametes which are derived from two different parents. For example:- cockroach, frog, human beings, and it is also called cross fertilization.
Types of sexual reproduction in animals on the basis of structure of fusing gamets syngamy is of three types:- 1) Isogamy, 2) anisogamy and 3) hologamy. Isogamy refers to when two fusing gametes are morphologically as well as physiological similar to each other such gametes are known as isogamy. For example in protozoan whereas anisogamy refers to when two fusing gametes are morphologically and physiological different from each other is known as anisogamy or heterogamy. For example in frog, rabbit and human beings however hologamy refers to when two organism themselves act as gametes is known as hologamy. For example yeast.
Syngamy in plants/ types of sexual reproduction in plants
Syngamy in plants refers to permanent fusion of two haploid male and female gametes that result in formation of diploid zygote letter on it will develop into to seed of fruit.
Types of sexual reproduction in plants generally involve syngamy and triple fusion. It means fusion of gametes two times, first triple fusion refers to fusion of one haploid male gamete (pollen) with two haploid polar nuclei that resulting triploid primary endosperm nucleus followed by syngamy which is refers to fusion of one haploid male gamete pollen with one haploid female gamete egg cell that resulting diploid zygote that letter on developed into embryo of seed in fruit while endosperm provide nourishment to developing zygotes. In plant, fertilization takes place two times that’s why it is known as double fertilization and it is only found in plants.
Lower plants like algae, bryophytes pteridophytes gymnosperms there is alternation of two generation observe are gametophyte and sporophyte. Gametophyte generally represent sexual phase of plant life cycle starts at haploid spore. By the process of mitosis spore change into haploid gametophytes that have male and female sex organ and produce a haploid gamete, two opposite haploid gametes fuse to form diploid zygote, this resulting zygote developed into a sporophytic phase of plant life cycle that have special structure known as a sporangium which form haploid spore by the process of meiosis.
Types of sexual reproduction in fungi
Types of sexual reproduction in fungi consist of plasmogamy, karyogamy and meiosis. Plasmogamy is the fusion of two protoplast containing ttwo cells, it brings two haploid nuclei close to each other, it is followed by karyogamy refers to fusion of two haploid nuclei to form diploid zygote, and karyogamy followed by meiosis in which zygote undergoes meiosis process and divide into haploid nuclei or spores to restore the haploid phase of life cycle of fungi.
Fungi also represent sexulity character, commonly bisexual fungi known as homothallic means presence of two thallus, and unisexual fungi commonly known as heterothallic means two different types thallus.
Conjugation in bacteria/ types of sexual reproduction in bacteria
Conjugation in bacteria generally represents temporary union of two organism that make connecting to each other by the formation of cytoplasmic bridge exchange the genetic material and micronuclei. After exchanging the genetic material and micronuclei they separated.
Conjugation refers to involves temporary pairing of two parents known as conjugants to exchange their male pronuclei for example it is found in bacteria and ciliate, protozoan such as paramecium
Types of sexual reproduction in bacteria represented by conjugation, it is transfer of genetic material from one bacteria to another bacteria by cytoplasmic Bridge. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor.