Question

Before the cell enters mitosis, mitotic CDK or cdc2 (cyclin dependent kinase) has to be activated by:

a.Phosphorylation by the kinases Cdc25 and CAK and dephosphorylation by Wee1

b.Binding to cycling, two phosphorylation events and one dephosphorylation

c.Binding to cycling is a necessary and sufficient to activate cdc2

d,Binding to cycling is a necessary however phosphorylation events are needed as well.

e.Binding to cycling, two phosphorylation events and one dephosphorylation

What experiment led to the discovery that there is a gap between S-Phase and Mitosis?

A short [3H] thymidine pulse labeling of cells and testing how long it will take the [3H] thymidine to be detected on mitotic chromosomes.

The fusion of synchronized cells by Sendai virus, an experiment done by Rao and Johnson.

The fusion of synchronized cells by Sendai virus, an experiment done by Rao and Johnson.

A short [3H] thymidine pulse labeling of cells, fixing them immediately on slides. Exposing them to a film, and counting how many cells show dark spots.

A different experiment not described here.

What will be the phenotype of a mitochondria that has less cristae than normal mitochondria?

It will allow the mitochondria to shrink.

The mitochondria will produce more water molecules.

The mitochondria will have less oxidative phosphorylation.

The mitochondria won’t be affected.

The mitochondria will produce less NADH but not less FADH₂ than normal.

Answer 1

Ans-1)Binding to cycling, two phosphorylation events and one dephosphorylation.

Ecplaination: MCDK activation involve following step:

Binding of MCDK to cyclin to form cDK - cyclin which is then phosphorylated at 161 theronine residue of CDK by CAK and dephosphorylation at 15th tyrosine and161 threonine residues by cdc25 phosphatse activity cause activation of MCDK.

Ans-2)A short [3H] thymidine pulse labeling of cells and testing how long it will take the [3H] thymidine to be detected on mitotic chromosomes.

Ans-3)

The mitochondria will have less oxidative phosphorylation.

Explaination:mitochondrial cristae are the site of oxidative phosphorylation so less the cristae no less will be oxidative phosphorylation