Final Exam - Cell Cycle

Question 1

What are the three phases of interphase?

Answer 1

G1 phase, S phase, G2 phase

Question 2

What occurs during the G1 phase?

Answer 2

gap phase; chromosomes in the nucleus

Question 3

What occurs during the S phase?

Answer 3

DNA synthesis and chromosome duplication

Question 4

What occurs during the G2 phase?

Answer 4

gap phase; cell with duplicated chromosomes

Question 5

What are is the M phase?

Answer 5

mitosis

Question 6

What are the phases of mitosis?

Answer 6

prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

Question 7

What happens during prophase?

Answer 7

• the replicated chromosomes, each consisting of two closely associated sister chromatids, condense
• outside the nucleus the mitotic spindle assembles between the two centrosomes

Question 8

What happens during prometaphase?

Answer 8

starts with the breakdown of the nuclear envelope

Question 9

What happens during metaphase?

Answer 9

• the chromosomes are aligned at the equator of the spindle midway between the spindle poles
• the kinetochore microtubules attach sister chromatids

Question 10

What happens during anaphase?

Answer 10

the sister chromatids synchronously separate to form two daughter chromosomes and each is pulled slowly toward the spindle pole it faces

Question 11

What happens during telophase?

Answer 11

• the two sets of daughter chromosomes arrive at the poles of the spindle and decondense
• a new nuclear envelope reassembles around each set, completing the formation of two nuclei, marking the end of mitosis

Question 12

What happens during cytokinesis?

Answer 12

the cytoplasm is divided in two by a contractile ring of actin and myosin filaments which pinches the cell in two to create two daughter cells

Question 13

What is the G0 phase?

Answer 13

cell cycle arrest

Question 14

What is the function of cyclins?

Answer 14

they are made and degraded cyclically in dividing cells

Question 15

What is the purpose of the G1/S-CDK complex?

Answer 15

initiates cell cycle entry

Question 16

What is the purpose of the S-CDK complex?

Answer 16

initiates DNA replication

Question 17

What is the purpose of the M-CDK complex?

Answer 17

initiates mitotic entry

Question 18

When are cyclin-dependent kinases activated?

Answer 18

only when their cyclin is around

Question 19

What is the function of Wee1?

Answer 19

inhibits Cdk through phosphorylation

Question 20

What is the function of cdc25?

Answer 20

counteracts the function of Wee1

Question 21

What is the function of CK1?

Answer 21

cdk inhibitor proteins bind to cdk-cyclin complex and physically block its ability to interact with other proteins

Question 22

What is a Rb?

Answer 22

retinoblastoma is a tumor supressor which arrests cells at the G1/S checkpoint and stop transcription by inhibiting E2F transcription factor

Question 23

In normal function, what is rb activated by?

Answer 23

G1-Cdk via Ras+MAP kinase pathway

Question 24

What is p53?

Answer 24

a tumor supressor

Question 25

What does p53 do?

Answer 25

senses DNA damage and arrests cell division at G2/M checkpoint if necessary

Question 26

What does the checkpoint kinase detect?

Answer 26

detects damage and signal pH of p53. Activates p53 which activates the transcription of p21=CDK inhibitor - cell cycle stops for repair

Question 27

What does Ras do?

Answer 27

stimulates cell division by indirectly inactivating Rb, liberating E2F and allowing the cell to pass through the G1/S checkpoint

Question 28

What are the cell cycle checkpoints?

Answer 28

• G1/S
• G2/M
• M/G1

Question 29

Where is the G1/S checkpoint located?

Answer 29

right before the S phase

Question 30

What ‘question’ does the G1/S checkpoint ask?

Answer 30

is the environment favorable

Question 31

Where is the G2/M checkpoint located?

Answer 31

right before M

Question 32

What ‘questions’ does the G2/M checkpoint ask?

Answer 32

is the DNA replicated

is the environment favorable

Question 33

Where is the M/G1 checkpoint located?

Answer 33

in the completion of mitosis/metaphase checkpoint

Question 34

What ‘question’ does the M/G1 checkpoint ask?

Answer 34

are all the chromosomes attached to the spindle

Question 35

What can happen if Rb is inactive of mutant?

Answer 35

cells enter S phase and form an aggressive tumor

Question 36

What is the treatment for an inactive or mutant retinoblastoma?

Answer 36

enucleation prior to metastasis

Question 37

What happens in psoriasis?

Answer 37

hyperplastic skin disease exhibiting as inflammation and excessive skin proliferation

Question 38

What happens in avian pox?

Answer 38

hyperplastic skin disease exhibiting as epidermal proliferation and hyperkeratosis