Question
Examine the model of the cell cycle, shown here. Which of these statements describes the events that occur in G1 and G2, but not S during interphase?
Responses
A Cell growth and genome duplication occur in G1 and G2.Cell growth and genome duplication occur in G1 and G2.
B DNA replication and cell division occur in G1 and G2.DNA replication and cell division occur in G1 and G2.
C Cell growth and cell cycle checkpoints occur in G1 and G2.Cell growth and cell cycle checkpoints occur in G1 and G2.
D Nuclear division and cytoplasmic division occur in G1 and G2.Nuclear division and cytoplasmic division occur in G1 and G2.
Responses
A Cell growth and genome duplication occur in G1 and G2.Cell growth and genome duplication occur in G1 and G2.
B DNA replication and cell division occur in G1 and G2.DNA replication and cell division occur in G1 and G2.
C Cell growth and cell cycle checkpoints occur in G1 and G2.Cell growth and cell cycle checkpoints occur in G1 and G2.
D Nuclear division and cytoplasmic division occur in G1 and G2.Nuclear division and cytoplasmic division occur in G1 and G2.
Answers
GPT-4o mini
To determine which statement correctly describes the events that occur in G1 and G2 but not in S phase during interphase, let's break down what happens in each phase:
- **G1 (Gap 1)**: This is the first phase of interphase where the cell grows, produces RNA, and synthesizes protein. During G1, the cell also undergoes various checks to ensure it is ready for DNA synthesis.
- **S (Synthesis)**: This phase is specifically for DNA replication (i.e., the synthesis of genetic material), where the cell duplicates its entire set of chromosomes.
- **G2 (Gap 2)**: In this phase, the cell continues to grow and prepares for mitosis. During G2, the cell checks for any DNA damage and ensures all DNA has been replicated accurately.
Now, analyzing the options:
A. **Cell growth and genome duplication occur in G1 and G2.** - This is incorrect because genome duplication (DNA replication) occurs only in the S phase.
B. **DNA replication and cell division occur in G1 and G2.** - This is incorrect because DNA replication occurs only in S phase, and cell division (mitosis) occurs after G2 in the M phase.
C. **Cell growth and cell cycle checkpoints occur in G1 and G2.** - This statement is correct because both G1 and G2 involve cell growth, and both have checkpoints to assess whether the cell should proceed to the next phase.
D. **Nuclear division and cytoplasmic division occur in G1 and G2.** - This is incorrect because nuclear division (mitosis) occurs after G2 in the M phase.
Based on this analysis, the correct answer is:
**C. Cell growth and cell cycle checkpoints occur in G1 and G2.**
- **G1 (Gap 1)**: This is the first phase of interphase where the cell grows, produces RNA, and synthesizes protein. During G1, the cell also undergoes various checks to ensure it is ready for DNA synthesis.
- **S (Synthesis)**: This phase is specifically for DNA replication (i.e., the synthesis of genetic material), where the cell duplicates its entire set of chromosomes.
- **G2 (Gap 2)**: In this phase, the cell continues to grow and prepares for mitosis. During G2, the cell checks for any DNA damage and ensures all DNA has been replicated accurately.
Now, analyzing the options:
A. **Cell growth and genome duplication occur in G1 and G2.** - This is incorrect because genome duplication (DNA replication) occurs only in the S phase.
B. **DNA replication and cell division occur in G1 and G2.** - This is incorrect because DNA replication occurs only in S phase, and cell division (mitosis) occurs after G2 in the M phase.
C. **Cell growth and cell cycle checkpoints occur in G1 and G2.** - This statement is correct because both G1 and G2 involve cell growth, and both have checkpoints to assess whether the cell should proceed to the next phase.
D. **Nuclear division and cytoplasmic division occur in G1 and G2.** - This is incorrect because nuclear division (mitosis) occurs after G2 in the M phase.
Based on this analysis, the correct answer is:
**C. Cell growth and cell cycle checkpoints occur in G1 and G2.**