LONG ESSAY QUESTIONS Compare and contrast Mitosis and Meiosis. Be detailed with

ID: 74281 • Letter: L

Question

LONG ESSAY QUESTIONS

Compare and contrast Mitosis and Meiosis. Be detailed with your explanation. Make sure you focus on:

All the stages in Mitosis

All the stages in Meiosis

What occurs during each stage of Mitosis and each stage of Meiosis

The number of chromosomes in each cell at the start, and the number of chromosomes in the cell at the end of Mitosis and Meiosis.

When crossing over occurs

How many daughter cells are produced for Mitosis and Meiosis

If the cells are haploid or diploid for Mitosis and Meiosis

What cells perform each process (somatic or sex cells)

Purpose of mitosis and purpose of meiosis

Explanation / Answer

Mitotic phase of cell cycle includes both mitosis (karyokinesis) and cytokinesis. In animal cells karyokinesis (separation of nucleus) is usually followed by cytokinesis (separation of cytoplasm).

Mitosis is usually divided into four stages, prophase, metaphase, anaphase, and telophase. During mitosis, the division of nuclear material starts with the doubling of chromosomes, followed by distribution between two daughter nuclei in equal proportion.

Prophase is the first phase of cell division in both mitosis and meiosis. During this phase, cohesion that is present throughout the length of the chromatids is removed except at the centromere. The chromatids become more visible during this phase.

Prophase is the first phase of cell division in both mitosis and meiosis. During this phase, cohesion that is present throughout the length of the chromatids is removed except at the centromere, this occurs commonly both in mitosis and meiosis. The chromatids become more visible during this phase.

In meiosis, Alignment of homologous chromosomes at Mid-Prophase –I is characteristic of meiosis. The two chromosomes sharing the same quality are called “homologous chromosomes.” These chromosomes crossover at some point and rejoin to form recombinant chromatids. Now, these chromosomes are separated at Anaphase-I and move to their opposite poles.

In contrast to meiosis, the synapse of homologous chromosomes does not occur in mitosis. During anaphase of mitosis, the sister chromatids get separated and move to the opposite poles. In contrast to mitosis, the “homologues chromosomes” (but not sister chromatids) move to the opposite poles in anaphase –I of meiosis. In meiosis, the separation of sister chromatids occur in anaphase –II.

During the metaphase, two chromatids are formed from each chromosome by longitudinal splitting. These chromatids form the chromosomes of daughter cells.

During anaphase, centromeres are pulled and the chromatids become separated and move towards the opposite poles. These chromatids now are the chromosomes of the daughter cells, and are pulled towards the centrioles by means of spindle fibres.

In the stage of telophase, cytoplasmic division of the cell takes place (cytokinesis) during which each of the daughter cell receives one of the daughter nuclei. The interval between each division is called interphase.

Mitosis

Meiosis

Occurs in vegetative cells

Occurs in reproductive cells

Daughter cells are identical to parent cells and are diploid.

Daughter cells are not identical to the mother cells and are haploid.

Number of daughter cells produced per each division are two

Number of daughter cells produced per each division are four

No genetic recombination occurs

Genetic recombination do occurs.

Number of chromosomes in mitosis at various stages are, Interphase = 2n, Prophase = 2n, Metaphase = 2n, Anaphase = 4n, Telophase = 4n, Cytokenisis = 2n

Number of chromosomes in meiosis at various stages are, Meiosis-I

Interphase = 2n, Metaphase = 2n, Anaphase = 2n, Telophase = 2n, Cytokenisis = n.

Meiosis-II:

Metaphase 2 = n, Anaphase 2 = 2n, Telophase 2 = 2n, Cytokenisis 2 = n.

The main purpose of mitosis is tissue growth

The main purpose of meiosis is reproduction and gene diversity.