Cell Cycle

Question 1

G1, S, G2, M Phases

Answer 1

Grow, Replicate DNA, Grow, Segregate DNA, Divide Cytoplasm

Question 2

Interphase

Answer 2

G1, S, G2

Question 3

Mitosis

Answer 3

Segregate DNA. Nuclear and cytoplasmic division. 5 distinct phases.

Question 4

Cytokinesis

Answer 4

Divide cytoplasm in two. Cytoplasm and organelle segregation + membrane scission.

Question 5

Prophase, Prometaphase, Metaphase, Anaphase, Telophase

Answer 5

(P)Parent cell chromosomes — which were duplicated during S phase — condense and become thousands of times more compact than they were during interphase. (P)Nuclear envelope breaks down and spindles attach to chromosomes. (M)Chromosomes line up at equator/plate (A)Sister chromatids are pulled apart. (T)Chromatids move to opposite ends and re-establish nuclear envelope.

Question 6

G1/S Checkpoint

Answer 6

Start checkpoint. Enter cell cycle and proceed to S phase. Is environment favorable?

Question 7

G2/M Checkpoint

Answer 7

Enter Mitosis. Is all DNA replicated correctly and is environment favorable?

Question 8

Spindle Assembly Checkpoint

Answer 8

Are all chromosomes attached to the spindle correctly?

Question 9

Metaphase-to-Anaphase Transition

Answer 9

Trigger anaphase and proceed to cytokinesis.

Question 10

Cyclin

Answer 10

Accumulate in mitosis. Goes up in mitosis, down in interphase.

Question 11

Cdk (Cdc2 in Fission Yeast)

Answer 11

Cyclin dependent kinase

Question 12

CyclinB/Cdk Complex = M-Cdk (Promotes M Phase)

Answer 12

Binding of M-Cyclin to Cdk activates the kinase (Cdk).

Question 13

CyclinA/Cdk Complex = S-Cdk (Promotes S Phase)

Answer 13

Binding of S-Cyclin to Cdk activates the kinase (Cdk).

Question 14

CAK- Cdk Activating Kinase

Answer 14

Causes structural change that activates the cyclin-CDK complex by phosphorylating the active site of Cdk. Cyclin-Cdk complex is now fully active.

Question 15

Wee1

Answer 15

Mutant yeast that prematurely enters G2/M transition and goes through mitosis. Wee1 encodes a kinase that inhibits M-Cdk (M-Cdk usually drives forward mitosis).

Question 16

Cdc25

Answer 16

Full activation of M-Cdk requires removal of the Wee1 inhibitory phosphate by Cdc25 phosphatase.

Question 17

APC/C (Anaphase Promoting Complex) - Different from APC involved in Wnt/Beta-Catenin Signaling

Answer 17

A ubiquitin ligase complex that targets M-cyclin for proteasomal degradation. Initiates chromatid separation.

Question 18

Cdc20

Answer 18

Cdk activates Cdc20 which is an activating subunit. It interacts with inactive APC/C to make active APC/C which will add ubiquitin and E1/E2 ubiquitylation enzymes that leave a polyubiquitin chain on M-cyclin that directs it for degradation by proteasome. Activated APC/C will also ubiquilize securing so that Separase is active.

Question 19

Securin

Answer 19

Prevents separase from doing its job; it inhibits separase.

Question 20

Separase

Answer 20

Binds to cohesions and cleaves them. Cohesions dissociate so chromatids can then separate.

Question 21

Cohesin

Answer 21

Ring like proteins that hold together sister chromatids.

Question 22

Ubiquitination

Answer 22

Mark for degradation in proteasome.

Question 23

Astral Microtubules

Answer 23

Brace against membrane.

Question 24

Kinetochore Microtubules

Answer 24

Bind to kinetochore

Question 25

Interpolar Microtubules

Answer 25

Lie adjacent to microtubules from opposite pole.

Question 26

Poleward Flux

Answer 26

The translocation of spindle microtubules toward spindle poles coupled to the depolymerization of their minus-ends and polymerization of plus-end. This is why speckles are seen moving further and further away from middle. Can shorten spindle microtubules during anaphase A, pulling chromatids to centrosomes. Anaphase B is motor driven, like Kinesin 5 pushing poles apart.

Question 27

Speckle Microscopy

Answer 27

Monitor microtubule dynamics. Speckles are almost like dye. We see that as time progresses on kymograph, the speckles move further away from the center. The dye/speckles originate from center of chromosomes.