Cell cycle

Question 1

The cell cycle in eukaryotes is divided into what 4 coordinated processes?

Answer 1

i) cell growth
ii) DNA replication
iii) distribution of the duplicated chromosomes to daughter cells
iv) cell division

Question 2

what are the two general phases of cell cycle?

Answer 2

Mitosis (M phase) involves nuclear division (also called karyokinesis) and is the most dramatic stage of the cell cycle, corresponding to the separation of daughter chromosomes and usually ending with cell division.
2. Interphase is the period between mitoses when the chromosomes are decondensed and distributed throughout the nucleus, so the nucleus appears morphologically uniform.

Question 3

quiescent, non- dividing phase

Answer 3

known as G0 stage, where the cells remain metabolically active but no longer proliferate

Question 4

What are the 4 cell cycle checkpoints?

Answer 4

1) G1: 2) S:
3) G2: 4) M:
1.G1:ensures damaged DNA is repaired before being replicated in S phase
2.S:continues monitoring DNA integrity
ensures DNA that is damaged during replication is repaired
3.G2:prevents initiation of mitosis if DNA is not completely replicated or is damaged
4.M:inhibits spindle assembly if chromosomes not distributed accurately to daughter cells

Question 5

cyclin

Answer 5

proteins which regulate the activity of the enzymes which regulate the cell cycle

Question 6

cyclin dependent protein kinases (Cdk􏰆s)

Answer 6

phosphorylating enzymes that are regulated by cyclins.

Question 7

What did the experiment with the frog oocytes show?

Answer 7

This cytoplasmic factor, which was named maturation promoting factor, or MPF, is a general regulator of the cell cycle that allows cells to complete cell division during both meiosis and mitosis.

Question 8

what did the budding yeast experiment show?

Answer 8

Specific protein kinases play a key role in progression of the cell cycle through its restriction point and its various checkpoints.

Question 9

what did the sea urchin embryo experiment show?

Answer 9

Specific proteins called cyclins (cyclin A and cyclin B) are rapidly synthesized and degraded in a manner synchronous with stages of the cell cycle

Question 10

cohesions

Answer 10

are proteins that bind to DNA in S phase & maintain the linkage between sister chromatids following DNA replication.

Question 11

condensins

Answer 11

are activated through phosphoryla-on,by,Cdk1 and Aurora B kinase and replace the cohesins (except those at the centromere) during mitosis; this is facilitated by the co-incident phosphorylation of cohesins by Cdk1 and Polo kinases

Question 12

cytokinesis

Answer 12

is coincident with the inactivation of Cdk1, but Aurora and Polo kinases remain active and co-ordinate the process

Question 13

where is the “should I divide” regulation?

Answer 13

late in G1.

Question 14

What are the checkpoints at “am i capable of dividing”

Answer 14

G1=damaged DNA
S=unreplicated or damaged DNA
G2=unreplicated or damaged DNA
M=chromosome misalignment