Question

The correct sequence of phases of cell cycle is:

• A. G1 $\to$ S $\to$ G2 $\to$ M
• B. M $\to$ G1 $\to$ G2 $\to$ S
• C. G1 $\to$ G2 $\to$ S $\to$ M
• D. S $\to$ G1 $\to$ G2 $\to$ M

Answer 1

The correct option is A G1 $\to$ S $\to$ G2 $\to$ M

Cell cycle is an orderly sequence of events during which a cell grows, duplicates its genetic material and then undergoes division.

Cell cycle includes two phases, interphase and mitotic (M) phase.

The interphase, though called the resting phase, is the time during which the cell is preparing for division by undergoing both cell growth and DNA replication in an orderly manner.

Interphase is divided into three phases, $G_1$ , S and $G_2$ phases.

During M phase (mitotic phase), the cell undergoes division and forms into two daughter cells. It includes karyokinesis and cytokinesis.

During karyokinesis, there is division of the nucleus. In cytokinesis, there is division of cytoplasm resulting in two daughter cells.

Hence the correct sequence of phases of cell cycle is:
$G_1$ $\to$ S $\to$ $G_2$ $\to$ M