Question

Identify the checkpoint that controls entry into DNA replication

• A. G\(_2\)/M checkpoint
• B. Spindle checkpoint
• C. G\(_1\)/S checkpoint
• D. Metaphase checkpoint

Hint:

Remember the checkpoints: \[ \boxed{ \begin{aligned} \text{G}_1/\text{S} &\rightarrow \text{Entry into DNA replication} \text{G}_2/\text{M} &\rightarrow \text{Entry into mitosis} \text{Metaphase} &\rightarrow \text{Spindle attachment} \end{aligned} } \]

Answer 1

The Correct Option is C

Step 1: Recall the major cell cycle checkpoints. The cell cycle contains three important checkpoints: \[ \begin{aligned} \text{G}_1/\text{S} &\rightarrow \text{Controls entry into DNA replication}, \text{G}_2/\text{M} &\rightarrow \text{Checks completion of DNA replication before mitosis}, \text{M checkpoint} &\rightarrow \text{Ensures proper chromosome attachment to spindle fibers.} \end{aligned} \]

Step 2: Identify the checkpoint for DNA replication. The \[ \boxed{\text{G}_1/\text{S}\text{ checkpoint}} \] determines whether the cell is ready to enter the S phase, where DNA replication occurs. Hence, \[ \boxed{\text{G}_1/\text{S checkpoint}} \] is the correct answer. Therefore, \[ \boxed{(C)} \] is the correct answer.