Which of the following can disrupt the cell cycle?

• A. Normal activity of proto-oncogenes
• B. Increased levels of cyclins
• C. Mutations in tumor suppressor genes
• D. Proper functioning of checkpoints

Answer: (C)

Verified step by step guidance

1. Understand the cell cycle: The cell cycle is a series of phases that cells go through to divide and replicate. It includes stages such as interphase (G1, S, G2) and mitosis (M phase).
2. Identify the role of proto-oncogenes: Proto-oncogenes are genes that promote cell division and growth. Their normal activity is essential for the cell cycle to proceed correctly.
3. Examine the function of cyclins: Cyclins are proteins that regulate the progression of the cell cycle by activating cyclin-dependent kinases (CDKs). Increased levels of cyclins can lead to uncontrolled cell division if not properly regulated.
4. Explore tumor suppressor genes: Tumor suppressor genes produce proteins that inhibit cell division, repair DNA, and ensure proper cell cycle checkpoints. Mutations in these genes can lead to a loss of function, allowing cells to divide uncontrollably, which can disrupt the cell cycle.
5. Consider the importance of checkpoints: Checkpoints in the cell cycle are critical for ensuring that each stage is completed accurately before moving to the next. Proper functioning of checkpoints prevents errors and maintains genomic integrity.