A gene that codes for a positive cell cycle regulator is called a(n) __. A kinase inhibitor B oncogene C proto-oncogene D tumor suppressor gene
The Correct Answer and Explanation is:
The correct answer is C proto-oncogene.
Explanation:
Genes play a critical role in regulating the cell cycle, which is the process by which cells grow and divide. A proto-oncogene is a normal gene that has the potential to become an oncogene (a gene that has the potential to cause cancer) if it undergoes mutations or increases its activity. Proto-oncogenes code for proteins that help regulate cell growth and division. These proteins may act as growth factors, receptors, or even enzymes like kinases, all of which help push the cell through the stages of the cell cycle.
For example, a proto-oncogene might code for a positive cell cycle regulator (like cyclins or cyclin-dependent kinases), which promotes cell division. However, when these proto-oncogenes are mutated, they can become oncogenes, leading to uncontrolled cell division and, in some cases, cancer.
Let’s break down the other options:
- A. Kinase inhibitor: These are molecules that inhibit the action of kinases. Kinases are enzymes that add phosphate groups to proteins, which is a crucial process in regulating the cell cycle. Kinase inhibitors are used in cancer therapy, but they are not responsible for promoting the cell cycle.
- B. Oncogene: This is a gene that, when mutated or overexpressed, has the potential to cause cancer. Oncogenes can be derived from proto-oncogenes, but the mutation leads to unregulated cell division, not normal regulation.
- D. Tumor suppressor gene: This type of gene helps prevent uncontrolled cell division. It acts as a negative regulator of the cell cycle. Tumor suppressor genes, like p53 and RB, halt the cell cycle in response to DNA damage, preventing damaged cells from dividing. When tumor suppressor genes are mutated, they lose their ability to control the cell cycle, which can lead to cancer.
Thus, a gene that codes for a positive cell cycle regulator is a proto-oncogene, which can potentially become an oncogene under certain conditions.
