Which sequence best describes apoptosis at the G1 checkpoint?

The correct answer is "Cdk/cyclin complex is inhibited→ p53 levels rise → p21 production increase".

Explanation:

The missing options of this question are:

A. p53 levels rise → p21 production increase → Cdk/cyclin complex is inhibited

B. p21 production increase → Cdk/cyclin complex is inhibited→ p53 levels rise

C. Cdk/cyclin complex is inhibited→ p21 production increase → p53 levels rise

D. Cdk/cyclin complex is inhibited→ p53 levels rise → p21 production increase

E. p53 levels rise → Cdk/cyclin complex is inhibited→ p21 production increase

The correct answer is option D. "Cdk/cyclin complex is inhibited→ p53 levels rise → p21 production increase".

Apoptosis is a process at which the cells undergo a programmed death. This mechanisms happens at G1 checkpoint first by the inhibition of Cdk/cyclin complex which causes p53 levels to rise and later, an increment of p21 production. First, a cyclin-dependent kinase inhibitor regulates the inhibition of the Cdk/cyclin complex. This causes p53 levels to rise, since p53 is a direct downstream kinase substrate for CDK. Subsequently, p21 production increase as well since p21 is a inhibitor of cyclin-dependent kinases.

the answers are as following:

1. c. double helix, nucleosome, coil, supercoil, chromosome

2. b. g2 phase, preparation for mitosis

3. d. interphase consists of the g1, s, and g2 phases

4. c. metaphase

5. a. chromosomes are duplicated before cell division so that each new daughter cell has a complete set