Question

The diagram represents a stage during cell division. Answer the following.
i. Name the parts labelled 1, 2
ii. Identify the above stage and give a reason to support your answer.
iii. Mention where in the body this type of cell division occurs.
iv. Name the stage prior to this stage and draw a diagram to represent the same.
v. Give any two difference between mitosis and meiosis.

Answer 1

i. The part labelled "1" is sister chromatids. These are the one half of the replicated chromosomes or the identical copies of DNA formed after the replication of chromosomes. Sister chromatids separate during Anaphase of Mitosis.

The part labelled "2" is Astral microtubules. These are the microtubules which emerge from the centrosomes but do not connect to the kinetochore. These are also called as sub-population of microtubules.

ii. The stage given in the image is Anaphase of Mitosis. In this phase, the sister chromatids separate from each other and move away from each other along the spindle fibers. This can be seen evidently in the image.

iii. Mitosis occurs in almost all the body parts. Mitosis results in the formation of two identical cells from single parent cell with similar genetic information. Mitosis is responsible for repair mechanism in skin and muscle tissue where the wearing of tissue happens more often. Mitosis does not take place during the division of germ cells.

iv. The stage prior to Anaphase is Metaphase. During mataphase, the chromosomes align themselves in the centre of the cell or the equatorial position of the cell, this is also called as metaphase plate. The separation of genetic material to form sister chromatids also happens during metaphase.

v. Mitosis occurs in almost all the organisms whereas meiosis occurs only in sex cells or germ cells of sexually reproducing humans, animals and plants.

Mitosis results in the formation of two identical cells with similar genetic information and same number of chromosome hence forming two diploid cells whereas, meiosis results in chromosome numbers reduced to half forming two haploid cells.