What is Reproduction?

Introduction

Reproduction is the process of production of offspring that are somehow genetically similar to the parents. The process makes sure about the continuity of the species one generation after the other. It is the principal constituent of life on Earth. The existence of every other living being is because of reproduction.

Types of Reproduction

Reproduction can take place in two ways and they are asexual and sexual. The process of asexual reproduction refers to the type of reproduction that takes place when a single organism gives rise to another organism such as the process of binary fission. The process does not involve the fusion of gametes, which is why the offspring are completely alike the parents.

Figure 1: Asexual Reproduction of yeast

The offspring that are produced as a result of the process is less diverse in nature. Generally, unicellular organisms such as the amoeba produce through this process. Through the process, lots of progenies can be generated without any mate but however the organisms so produced do not have varieties to their parents and have the same deficiencies, and are susceptible to the diseases.

Through the process of sexual reproduction, an offspring is produced by the fusion of both the male and the female gametes. The two types of gametes can be contributed by the same organism or two different organisms. Compared to asexual reproduction, this process is slower and complicated. The organisms are very diverse genetically. They have the tendency to evolve around the altering situations of the climates. Many multicellular organisms including humans undergo this type of reproduction process.

Types of Sexual Reproduction

There are two types of sexual reproduction and they are syngamy and conjugation. Through the process of syngamy, there is the fusion of the two haploid sex cells that results in the formation of a diploid zygote. In other words, syngamy refers to the process of fertilization. It is a very common kind of reproduction in multicellular sexual populations including humans. Syngamy is the permanent fusion of two cells.

Syngamy is generally carried out by multi-cellular organisms such as humans, plants, and animals. Based on the type of the site of fertilization, syngamy can be of the types of internal and external fertilization. Based on the kinds of the source of the gametes, the process can be classified as autogamy and allogamy. Based on the structure of the gametes the process can be described as isogamy and anisogamy.

Through the process of conjugation, two different organisms come together for temporary fusion for the transfer of the micronuclei material. The process can be noticed in many single-celled organisms such as bacteria, protozoans, and single-celled fungi. Most unicellular organisms undergo the process of conjugation for reproduction.

Reproduction in Plants

Reproduction in plants takes place through both the asexual and the sexual kinds. Asexual reproduction in plants takes place through the process of vegetative propagation, fragmentation, budding, formation of spore, and micropropagation. Through the process of vegetative reproduction, the different parts of the plants, that is the leaves, stems, and buds take part, and a new plant is produced from a single plant.

Figure 2: Vegetative Reproduction in Plants

Budding generally occurs in yeast and yeast-like cells, where bud-like projections detach from the parent cell and grow into a new individual. Fragmentation is the ability of some organisms to form fragments and get separated. The spores can germinate and grow into beings under suitable conditions. Through the process of micropropagation new progeny is created in the lab providing favourable nutrients and conditions to an explant.

Through the mode of sexual reproduction, plants reproduce by pollination, fertilization, and others. In pollination, the pollen grains from the anthers are transferred to the stigma of the same or different plant. Fertilization is the process of fusion of the gametes that later develop into the embryo.

Reproduction in Animals

Animals reproduce asexually through the process of binary fission, budding, fragmentation, regeneration, and parthenogenesis. Binary fission is generally found in the prokaryotes such as bacteria. The organelles and the cytoplasm enlarge in size and then detach from the parent.

Figure 3: Binary Fission in Ameoba

Fragmentation takes place in planarians where the body breaks down into fragments and grows into different beings. Regeneration takes place in echinoderms. Parthenogenesis is the formation of eggs. Sexual reproduction is the process of fusion of male and female gamete for the production of a new being. Many organs are involved in the process.

Figure 4: Reproduction in Earthworm

Molecular Reproduction

The process of molecular reproduction involves the DNA molecules acting as the codes by which the genetic information is stored. Under the code, DNA synthesizes a strand of RNA, and this RNA acts as the messenger carrying the genetic code to sites in the cells where the proteins are synthesized.

Levels of Reproduction

The levels of reproduction can be described as the replication at the levels of molecules, reproduction of the cell, binary fission, and multiple fission. In the first section, the organism gets genetic information from the parent cell. Most of the algae, protozoans, and moulds, get divided by the process of fission.

Conclusion

Reproduction is the process by which new progenies are developed from the old progenies. The process can be seen in all kinds of organisms. Generally, the modes of the process are not the same and broadly the two types by which it is classified are sexual and asexual forms. At the molecular level, the genetic code that carries much of the information of the parents is transferred to the progenies.

FAQs

Q1. What are the types of reproduction?

Ans. There are mainly two types of reproduction which include asexual and sexual reproduction. Sexual reproduction better fosters the growth of genetic diversity through the amalgamation of new alleles during fertilization and meiosis. On the other hand, asexual reproduction is more energy effective and rapid.

Q2. What are the types of asexual reproduction?

Ans. Asexual reproduction comprises of different types which includes binary fission, budding, fragmentation, vegetative propagation and sporogenesis. This type of reproduction is demonstrated as the reproduction type in which the new offspring is generated by a single parent. This type of reproduction seems to appear in both unicellular and multicellular organisms.