Question

4. Short response (2 sentences max, 6pts each) A. Many yeast species have only one cyclin-dependent kinase (Cdk), which activates protein targets that drive events in multiple phases of the cell cycle. Why doesn't this Cdk activate G1-, S-, G2-, and M-phase proteins all at the same time? B. Please describe how cell death by apoptosis can play a beneficial role in the body's healthy growth. C. For a cell starting in G1, place the following cell cycle events in order A. Actin & myosin act on the contractile ring B. Centrosomes are duplicated C. Condensin is activated D. Ndc80 attaches to spindle microtubule:s E. S-phase cyclins are expressed START AT D. How do the proteins integrin and cadherin play a role in the progression of tumors from benign to malignant?

Answer 1

Ans a) Cdk is a cyclin dependent kinase which helps in the cell cycle progression and regulators. They start the production of proteins one by one for the stages of the cell cycle. This is because the Cdk present at different stage are different where G1 cyclin helps to produce G1 proteins, G1/S helps in passing the cell cycle through G1 and into S phase, S cyclin produce produce proteins needed for S phase and M-cyclin for M-phase. They all don’t express at same time because they get signal to produce protein only when required and cell has passed through a particular stage.

Ans b) Apoptosis plays an important role in health of the body as it helps in eliminating the unwanted, damaged and improperly formed cells. They also help in strengthening the immune by removing the cell that are infected or have certain predisposition towards cancer formation.