Question

What are the steps for division of the genome (mitosis), including major events?

Answer 1

The fundamental processes of life is mitosis in which the contents of cell are duplicated ( including chromosomes) and later broken into two identical daughter cells. The mitosis helps in the separation of duplicated genetic material present in the nucleus and thus parents cell genome is transfered into two daughter cells.

Mitosis has been divided into five stages:

1. Prophase: It is the first step of mitosis during which condensation of chromosomes takes place. also during this process the two pairs of centrioles move to opposite poles and this leads to the formation of spindle.

2. prometaphase: It begins with the breaking of nuclear envelope , which is important for spindle assembly because centrosomes are outside the nucleus and the spindle gets access to chromosomes after membrane breakage.during the progress of prometaphase chromosomes are pulled towards the opposite poles by the microtubules.

3. Metaphase: it is the stage when chromosomes can be easily viewed, as their centromeres get aligned at the equator of the spindle. the proper assembling of spindle is checked by various check points before cell enters Anaphase.

4. Anaphase: As the cell enters Anaphase sister chromatids get separated and the chromosomes move to opposite poles of cell. Thus, during anaphase it is ensured that each daughter cell receives identical chromosomes.

5. The end stage of mitosis is telophase. At this stage the following changes occur within the cell:

i. chromosomes reach the poles.

ii. reformation of nuclear membrane.

iii. Decondensation(uncoiling) of chromosomes.

Finally by the process called Cytokinesis, the parental cytoplasm is divided into two daughter cells.