Cell Cycle

Question 1

interphase

Answer 1

duplication of cell’s contents
-90% of cells growth cycle
G1, S, G2

Question 2

G1

Answer 2

first growth phase
cell commits to continue division OR exit from cell cyel

Question 3

S

Answer 3

DNA replication
-each chromosome now composed of 2 chromatids
–tied together by cohesion molecules that form ring around chromatids (SMC1 and SMC3)

Question 4

G2

Answer 4

final growth phase

Question 5

G1 -> S

Answer 5

mitogenic stimulus present, signal transduction cascade initiated
results in expression of genes needed to proceed to S phase
cell committed after this!!!

Question 6

mitosis

Answer 6

division of cellular material into 2 separate cells
5 phases

Question 7

Quiescence (G0)

Answer 7

exit
not enough nutrients or growth conditions to replicate

Question 8

prophase

Answer 8

chromatin condenses
-chromosome becomes visible
centrosomes separate
-move to opposite sides of nucleus
mitotic spindle formation
-separate 2 sister chromatids

Question 9

condensins

Answer 9

-protein complexes that condense chromosomes to be easily segregated later
-SMC2 and SMC4 subunits
-cyclin-cdk complex phosphorylate condensins, resulting in assembly on chromosome

Question 10

prometaphase

Answer 10

nuclear envelop breaks down
-allows spindle microtubules to access sister chromatids
-result of phosphorylation of nuclear pore proteins and lamins
chromosomes become more condensed
kinetochore formed at centromere
microtubules attached to kinetochore

Question 11

metaphase

Answer 11

chromosomes align on metaphase plate
mitotic spindle checkpoint
–each kinetochore must attach by spindle microtubule so each daughter cell gets copy of each chromosome

Question 12

aster MT

Answer 12

holds centrosome in place at poles of mitotic spindle
“anchors”

Question 13

kinetochore MT

Answer 13

attached kinetochore on each side of sister chromatids, links chromosomes to spindle pores
Linkers to sister chromatids

Question 14

interpolar MT

Answer 14

2 microtubules from opposite poles interact w each other through motor proteins in middle of spindle pole
-provide rigid backbone for traction when we pull apart
-not associated w kinetochore

Question 15

Anaphase promoting complex

Answer 15

E3 ligase that tags securin for degradation by ubiquitinating it

Question 16

adenomatous polyposis coli

Answer 16

not an E3 ligase and does NOT ubiquitinate
-part of complex that phosphorylates B-catenin for degradation (wnt pathway)

Question 17

securin

Answer 17

keeps separase inactive

Question 18

separase

Answer 18

cleaves cohesion complex
mediates separation of sister chromatids

Question 19

anaphase

Answer 19

each centromere splits-> 2 free chromatids
each chromatid moves toward pole
cell begins to elongate, caused by movement of motor proteins along interpolar microtubules

Question 20

anaphase A

Answer 20

chromosomes move toward opposite poles as kinetochore associated microtubules depolymerizes at + end

Question 21

anaphase B

Answer 21

the elongation and sliding of interpolar microtubules paste one another pushes 2 poles apart

Question 22

telophase

Answer 22

2 sets of chromosomes arrive at poles of spindle
reformation of nuclear membrane and nucleus occurs
formation of cleavage furrow
division of cytoplasm begins w assembly of contractile ring

Question 23

cytokinesis

Answer 23

cytoplasm divided into 2 by contractile ring of actin and myosin filaments
-pinch off to create 2 diploid daughter cells

Question 24

cdk

Answer 24

cyclin dependent protein kinases
-serine/thronine kinase
only active when bound to cyclin
cdk1, cdk2, cdk4/6
concentrations remain constant throughout the cell cycle
cdk activity oscillates

Question 25

cyclin

Answer 25

proteins that controls progression of cell cycle through interactions w cdks concentration oscillates during cell cycle

Question 26

cdk inhibitors

Answer 26

cyclin D-cdk4/6 inhibitor: p16Ink4a general cyclin-cdk inhibitor: p21 and p27 terminated through ubiquitination

Question 27

anaphase promoting complex/ cyclosome

Answer 27

directs degradation of cyclins cdc20 and cdh1 are associated adaptor proteins that gives complex target specificity

Question 28

skp1/Cul1/ F0box complex

Answer 28

directs degradation of CKI

Question 29

g1-> S proteins involved

Answer 29

Rb-E2F joins (inactive) cyclin d-cdk4/6 AND cyclin E-cdk2 activated -Rb phosphorylated (inactivated), E2F free to induce S phase

Question 30

s phase initiation

Answer 30

ORC binds to origins of replication on chromosomes, bound by MCM and kept inactive by cdc6 cycline-cdk2 phosphorylates cdc6 marking for degradation ORC/MCM complex is free

Question 31

g2-> m phase

Answer 31

cyclin B accumulates and rises inactive state maintained by Wee1 near end g2, cdc25 phosphatase activates and removes wee1 -phosphorylation by CAK -cyclin B-cdk1 active----> mitosis

Question 32

positive feedback loop

Answer 32

activates cyclin b-cdk1 complex can phosphorylate (activate) cdc25 phosphatase-> increase the amount of active cyclin B-cdk1

Question 33

cyclin b-cdk1 role in prophase

Answer 33

phosphorylates condensin subunits so sondensin assembles on chromosome

Question 34

cyclin b-cdk1 role in prometaphase

Answer 34

phosphorylates nuclear pore protein and lamins to breakdown nuclear lamina

Question 35

cyclin b-cdk1 role in metaphase

Answer 35

phosphorylates microtubule associated proteins to form interpolar microtubule connection and formation of mitotic spindle

Question 36

g1 checkpoint

Answer 36

IF DNA DAMAGED/ INCOMPLETE p53 acts as TF and induces expression of p21 thta binds to cyclin d-cdk 4/6 and cyclin e-cdk2 --cause cell cycle arrest in G1 or S

Question 37

G2/M checkpoint

Answer 37

IF DNA DAMAGED/ INCOMPLETE phosphorylated p53 induces expression of p21 which binds cyclin b-cdk1 to arrest cell cycle

Question 38

mitotic spindle checkpoint

Answer 38

if microtubules not attached to kinetochore of sister chromatid pair, cell will not proceed to anaphase

Question 39

the sister chromatid are unable to be tied together and move past S phase. which moleucle must be mutated?

Answer 39

Cohesin

Question 40

the cyclin-dependent protein kinase that specifially works on the G phase and is associated w CyclinD inhibition. which of the following is most likely causing the inhibition?

Answer 40

p16Ink4a