Question

Postmitotic gap phase and synthetic phase refer to

• A. $G_2$ and M
• B. $G_1$ and S
• C. $G_2$ and S
• D. S and $G_1$

Answer 1

Answer: (B)

$G_1$ and S

$G_1$ phase (First growth phase or Post mitotic gap phase) is the first phase within interphase, from the end of the previous M phase until the beginning of DNA synthesis, is called $G_1$ (G indicating gap). It is also called the growth phase. During this phase, the biosynthetic activities of the cell, which are considerably slowed down during M phase, resume at a high rate. The duration of $G_1$ is highly variable, even among different cells of the same species.$G_2$ phase is the pre-mitotic gap phase. It is the period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis. It this phase, duplication of centriole, mitochondria, chloroplast occurs. The spindle proteins (Tubulin) are also synthesized. After mitosis, the cell enters the $G_1$ or the growth phase and then continues with DNA synthesis in the S phase which is followed by the $G_2$ phase.
So, the correct option is B.