As we all know, an organism is made up of about a hundred trillion cells. All these cells are actually come from a single cell. Therefore, cell division is crucial for the growth and reproduction of organisms. There are two types of cell division – mitosis and meiosis. In this essay, I will compare and contrast the processes of mitosis and meiosis, and also, discuss the roles and significance of mitosis and meiosis in the life of flowering plants and mammals. Mitosis is the process by which a cell separates the chromosomes in its cell nucleus into two identical sets, in two separate diploid nuclei.
Meiosis is a two-part cell division process in sexually reproducing organisms, which results in gametes with one-half the number of chromosomes of the parent cell. For the comparison and contrast of the processes of mitosis and meiosis, let us focus on their similarities. Firstly, during interphase, both mitosis and meiosis involve replication of chromosomes. Secondly, during prophase, the nuclear membrane of the both cells that undergoing mitosis and meiosis disintegrates. Thirdly, during metaphase, the chromosomes line up and each of them are attached to the spindle fibres in both mitosis and meiosis.
Fourthly, during anaphase, the chromosomes are pulled by spindle fibres into two halves and move to opposite poles of the cell in both types. In the meantime, the cytoplasm starts to divide in both mitosis and meiosis. Lastly, during telophase, new nuclear membranes form around each set of chromosomes in mitosis and meiosis. On the other hand, there are differences between the processes of mitosis and meiosis. Firstly, during prophase, the members of each pair of homologous chromosomes pair up in meiosis, but not in mitosis.
Furthermore, in meiosis, crossing over may occur in this stage. A small part of DNA of the members of chromosomes will be exchanged, result in variation of genes. Nevertheless, this will not happen in mitosis. Secondly, during anaphase, in mitosis, the two chromatids of each chromosome separate, while in meiosis, the two members of each homologous pair separate. Thirdly, during telophase, chromosomes of cell in mitosis uncoil to become chromatin again, but those in meiosis do not. Lastly, after telophase, mitosis comes to the end. However, meiosis continues.
The cell undergos second meiosis after that which the sister chromatids separate and finally results in four daughter cells. Although the processes of mitosis and meiosis are quite different, both of them contribute a lot to every organism. In both flowering plants and mammals, mitosis plays an important role in growth and development. Mitosis provides new cells for the growth of multicellular organisms. In the growth of plants, new undifferentiated cells are produced by mitosis continuously throughout the plants’ life in the region of cell division of meristems.
Besides, it allows cell replacement. Newly-produced cells replace worn-out or damaged cells regularly in mammals, especially in skin and blood. For flowering plants, asexual reproduction is carried out by mitosis. Flowering plants produce identical offspring by vegetative propagation. Gladiolus is one of the examples that reproduce asexually by developing corms. New corm is developed by mitosis which is supported by the energy from the stored food of previous corm and photosynthesis of young green leaves.
Mitosis is significant in asexual reproduction since desirable characteristics can be retained in the offspring. Also, no external agents required and it occurs at a relatively past rate while offspring obtain food directly from parents. For meiosis, it is important for sexual reproduction in both flowering plants and mammals. In flowering plants, male gametes and female gametes, which are carried in pollen grains or ovules, are produced in stamens and carpels of a flower respectively by meiosis.
After that, male and female gametes meet by pollination and follow by fertilization to produce offspring. In mammals, sperms and ova are produced in testes and ovaries respectively by meiosis. After ejaculation, one of the sperms meets an ovum. Fertilization occurs if their nuclei fuse together to form a zygote. Consequently, offspring can be produced. Due to the random distribution and independent assortment of pairs of homologous chromosomes, genetic variations among gametes are provided. The zygotes formed will have different genetic combinations from their parents.
In sexual reproduction, offspring show genetic variations which help them adapt to changes in the environment. Furthermore, transmission of diseases from parents to offspring is less likely to happen. In conclusion, both mitosis and meiosis play a significant role in the life of flowering plants and mammals. Mitosis participates in growth and development in organisms and also asexual reproduction in flowering plants and single-celled organisms; while meiosis contributes to sexual reproduction in both flowering plants and mammals. Mitosis and meiosis are essential to every organism lives on the earth.