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PinkMonkey Online Study Guide-Biology

Comparison between mitosis and meiosis

Mitosis

  1. It takes place continuously in body cells or somatic cells.

  2. The process is completed in one sequence or phase.

  3. DNA replication takes place during interphase.

  4. The duration of prophase is short usually of a few hours.

  5. Homologous chromosomes do not show pairing or synapsis.

  6. Chromosomes do not show crossing over a chiasmata.

  7. Division of the centromeres or kinetochores takes place during anaphase.

  8. Each of the cells formed contains the same number of chromosomes as in the parent cell.

  9. Each diploid cell produces two diploid cells.

  10. Shuffling of chromosomes does not take place.

  11. Chromatids separate during anaphase.

  12. The genetic constitution of the daughter cells is identified to that of the parent cells.

Meiosis

  1. It takes place during the process of gametogenesis to form germ cells.

  2. It is completed in two succesive divisions which occur one after the other.

  3. DNA replication takes place during interphase I but not in interphase II.

  4. The duration of prophase is comparatively longer and may take days.

  5. Homologous chromosomes show pairing or synapsis.

  6. Chromosomes show crossing over at chiasmata.

  7. There is no division of the centromeres during anaphase I. They divide only during anaphase II.

  8. Each of the cells formed contains half the number of chromosomes.

  9. Each diploid cell produces four haploid cells.

  10. Shuffling of chromosomes takes place resulting in different combinations of chromosomes.

  11. Homologous chromosomes (not chromatids) separate in anaphase I.

  12. The genetic constitution of the daughter cells differs from that of parent cell due to crossing over and recombinations.

Syngamy

Syngamy is the fusion of two haploid nuclei or gametes.

Click here to enlarge
Figure 14.20 Syngamy


When syngamy takes place between the two identical gametes, it is called isogamy and when it takes place between the two dissimilar gametes, it is called anisogamy. As in higher organisms, when it takes place between a large, passive receptive gamete called an egg and a small active (motile) initiative gamete called sperm, it is called oogamy.

Meiosis leads to the formation of haploid sex cells or gametes which are individually incapable of further development. Thus, the sex cells or gametes are arrested in their growth, but the syngamy removes the arrest and the diploid condition is restored. The diploid zygote formed by the union of haploid gametes is potentially capable of developing into a new individual.

Table of Contents

14.0 Introduction
14.1 Kingdom : Monera
14.2 Kingdom : Protista
14.3 Kingdom : Plantae
14.4 Kingdom : Fungi

Chapter 15





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