Question

What will be the amount of DNA in meiosis 2 products, if meiocytes contain 30pg DNA in G phase?
A. 30pg
B. 60pg
C. 15pg
D. 120pg

Answer 1

Hint: Cell division is important for new organisms to flourish. G2 phase also called gap 2 is a part of the interphase. In this phase, mitotic division takes place twice to make four haploid daughter cells. This phase mainly helps in protein synthesis.

Complete answer:
The M phase represents the phase when the actual cell division or mitosis occurs and the interphase represents the phase between the two successive M phases. It starts with the nuclear division, corresponding to daughter chromosomes (karyokinesis) and usually ends with the division of cytochrome (cytokinesis). The interphase is called the resting phase and it is the time during which the cell is preparing for division by undergoing both cell growth and DNA replication.

It is divided into 3 phases: G1 phase, S phase and G2 phase. Let us study the G2 phase:
G2 phase is the third phase of the interphase of the cell cycle that precedes mitosis. It ends with the onset of prophase, the first phase of mitosis in which the cell's chromatin condenses into chromosomes. It is the phase of rapid cell growth and protein synthesis during which the cell prepares for mitosis.

In the G2 phase, during the S phase, DNA replication begins in the nucleus, and the centriole duplicates in the cytoplasm. During the G2 phase, proteins are synthesised in preparation for mitosis while cell growth continues.

In the above question, we are given 30pg DNA in the G phase. It gets doubled in the S phase of the cell cycle by the process of replication to get 60 pg. After meiosis I, DNA content gets equally divided into the two cells which means each cell is 30pg. Both the cells undergo further division to form 4 haploid cells during the process of meiosis II. That means the content is further reduced to half i.e 15 pg DNA in each cell(M II).

So, the correct answer is option C, 15pg.

Note: Mitosis or an equational division is restricted to diploid cells. It usually results in the production of diploid daughter cells with identical genetic components. A very significant contribution of mitosis is cell repair. The cells of the upper layer of the epidermis in plants, cells of the lining of the gut and blood cells are constantly being replaced.