Bio exam 4 ch 10

Question 1

Eukaryotic cell cycle regulation

Answer 1

-Tightly regulated
-Checkpoints
-Regulators

Question 2

G1 checkpoint

Answer 2

-Restriction point
-Commits cell to dividing
-Is DNA damaged?

Question 3

G2 checkpoint

Answer 3

-Was DNA replicated correctly

Question 4

M checkpoint

Answer 4

-Metaphase
-Are chromosomes lined up correctly
-Are they attached to spindle correctly

Question 5

Interphase

Answer 5

-G1, S, G2
-Growing, replicating DNA
-2 checkpoints

Question 6

M phase

Answer 6

-Mitosis
-Splitting of cytoplasm, cytokinesis, formation of 2 daughter cells
-1 checkpoint

Question 7

How to move past checkpoints

Answer 7

-Positive regulators must be “Turned on”
-Negative regulators must be “Turned off”

Question 8

Positive regulators

Answer 8

-Cdk and Cyclin

Question 9

CDK

Answer 9

-Positive regulator enzyme
-Activated by binding cyclins
-Phosphorylates target proteins that regulate cell cycle

Question 10

Cyclin

Answer 10

-Binds to CDK
-Proteins that are made then broken down at specific times

Question 11

Negative regulators (G1 checkpoint)

Answer 11

-Retinoblastoma (Rb)
-P53

Question 12

Retinoblastoma (Rb)

Answer 12

-Monitors cell size
-Active, dephosphorylated binds to transcription factor, E2F: Blocks G1/S transition
-As cell size increases, Rb is phosphorylized and inactivated. Rb releasees E2F which turns on genes for cell cycle progression

Question 13

P53

Answer 13

-Monitors DNA damage
-If DNA is damaged p53 halts cell cycle and recruits DNA repair enzymes
-If DNA can’t be repaired, P53 triggers apoptosis
-As p53 levels rise, P21 is triggered to inhibit CDK/cyclin (halting progression)

Question 14

Cancer and cell cycle

Answer 14

-Correct number cells requires balance between cell division and apoptosis
-Too much or too little of one causes tumors

Question 15

Proto-Oncogene

Answer 15

-Positive cell cycle regulator
-If mutated to become oncogene that is overabundant, results in tumor

Question 16

Tumor supressor

Answer 16

-Negative cell cycle regulator
-Helps control cell cycle progression (blocking)
-If mutated and inactivated cam result in tumor