Cell Cycle

Question 1

stages in interphase

Answer 1

G1, S, G2

Question 2

mitosis stages

Answer 2

prophase, metaphase, anaphase, telophase

Question 3

mitochondria and chloroplasts divide via

Answer 3

binary fission

Question 4

prophase

Answer 4

nuclear envelope degrades, chromosomes condense

Question 5

metaphase

Answer 5

chromosomes attach to microtubules via kinetochores

Question 6

anaphase

Answer 6

microtubules shorten

Question 7

telophase

Answer 7

chromosomes decondense, cells reassemble nuclear membrane

Question 8

G1

Answer 8

cell grows, synthesis of RNA and proteins for DNA synthesis

Question 9

S

Answer 9

synthesis; active replication of chromosomes

Question 10

START

Answer 10

cell committed to cycle past this point

Question 11

checkpoints in cycle

Answer 11

• between G1 and S – checks for DNA damage before S phase
• G2 – checks to see that all DNA is replicated before mitosis
• M – all chromosomes attacked to spindle

Question 12

types of yeast cells we see in experiments

Answer 12

• budding yeast (s. cerevisiae)
• fission yeast (s.pombe)

Question 13

organisms used in meiosis study

Answer 13

frog eggs and urchin eggs

Question 14

cell cycle and mitotic cyclin

Answer 14

Question 15

MPF

Answer 15

dimer of cyclin and CDK

Question 16

APC

Answer 16

anaphase promoting complex; leads to ubiquination of cyclin

Question 17

what allows separation of sister chromatids at onset of anaphase?

Answer 17

APC directed by CDC20 to cause protease activity against securin, causing the activation of separase

Question 18

what inhibits separase?

Answer 18

• binding of securin
• -mitotic CDKs by phosphorylation of separase

Question 19

Wee1 mutant gene

Answer 19

defective wee1 gene activates mitotic CDKs too early (mutants are thus smaller)

• same result with mutant CDK1

Question 20

wee1

Answer 20

• phosphorylates CDKs on inhibitory tyosine 15 (Y15)
• CAK phosphorylates T161 –> activates CDK
• cdc25 is a phosphatase that removes phosphate for Y15 – opposes wee1
• now MPF is active
• cdc25 essential for entry into mitosis

Question 21

cells with mutation in cdc25+ gene

Answer 21

end up arresting in G2; essential for mitosis

Question 22

acronym cdc

Answer 22

controller of cell division

Question 23

mitotic cyclins synthesized during ___ phase

Answer 23

S phase

Question 24

what restrains mitotic CDK activity during S and G2

Answer 24

phosphorylation on CDK subunit

Question 25

need cyclin for transition into \_\_

Answer 25

S phase

Question 26

order of cyclin cycle

Answer 26

D → E → A → B

Question 27

mitotic cyclin and CDK levels throughout cell cycle

Answer 27

Question 28

cycle of cyclin B

Answer 28

increasing toward mitosis then drops to lowest point right at the end of mitosis

Question 29

only cyclin with external control

Answer 29

cyclin D

Question 30

transition of cyclin __ to ___ trips us into mitosis

Answer 30

A to B

Question 31

pathway starting with extracellular signal to cyclin D

Answer 31

Question 32

Retinoblastoma (Rb)

Answer 32

* raises cyclin E levels * cyclin D activates CDK 4/6 → phosphorylation of Rb * Rb releases E2F → E2F serves as a transcription factor * E2F targest cyclin E → cyclin E levels rise

Question 33

p53

Answer 33

* transcription factor found at DNA damage checkpoints * in the absence of p53 the cell cycle does not stop * oncogenes could be turned on

Question 34

p21 CIP

Answer 34

inhibits CDK