Question

a gene that codes for a positive cell cycle regulator is called a(n) ______.○ cyclin-dependent kinase○ kinase inhibitor○ tumor suppressor gene○ oncogene○ proto-oncogene

Explanation:

• Cyclin-dependent kinase is a protein (not a gene) that acts as a positive regulator.
• Kinase inhibitors negatively regulate cell cycle progression.
• Tumor suppressor genes are negative cell cycle regulators.
• Oncogenes are mutated proto-oncogenes that cause uncontrolled cell division, not normal positive regulators.
• Proto-oncogenes are the normal genes that code for positive cell cycle regulators, promoting proper cell growth and division.

Answer:

E. proto-oncogene