Questions:

Q1. The role of ‘cyclin' in the regulation of the cell cycle would be best compared to:

1. a digital watch that produces a precisely timed signal every few microseconds.
2. a row of dominoes, that all fall sequentially after the first one is flipped.
3. a light switch that alternates between on and off states.
4. the accumulation of sand in an hourglass.

 

Q2. All of the following statements correctly describe M-Cdk, EXCEPT:

1. M-Cdk causes the cell to enter S phase and begin DNA replication.
2. M-Cdk has two subunits, a protein kinase and a cyclin-type protein.
3. M-Cdk only becomes active during M-phase.
4. M-Cdk triggers many events by phosphorylating other proteins.

 

Q3. Enumerate the cell cycle check points. Why does the cell enter the G0 phase.

Q4. Cyclins are targeted for destruction through ubiquination. Descibe the process.How are Cyclin dependent kinases (CDks) activated?

Q5. Different cyclin-Cdks are responsible for triggering different stages of the cell cycle. Elaborate.

Q6. Are the genes that code of checkpoints most likely to be protooncogenes or tumor suppressor genes? Explain.

Q7. What happens to the cell cycle when DNA is damaged?