cell cycle regulation

Question 1

why do cell divide?

Answer 1

grow in size

to replace old and damaged cells

reproduction

Question 2

Categories of cells

Answer 2

— Cells that no longer divide after they differentiate

— Cells that normally don’t divide but can be induced to divide w/ proper stimulus (liver cells, lymphocytes)

— Cells w/ relatively high level of mitotic ability (stratum germinativum of skin, tunica mucosa of intestine, meristematic tissues of plants)

Question 3

Checkpoint control point system

Answer 3

cell cycle controlled by STOP & GO chemical signals at critical points

signals indicate if key cellular processes have been completed correctly

Question 4

restriction point

ensures the environment is favorable for DNA replication

Answer 4

G1/S

Question 5

Checks for DNA damage and ensures replication is complete

Answer 5

G2/M

Question 6

Ensures all chromosomes are properly attached to the mitotic spindle before separation

Answer 6

Metaphase/Anaphase checkpoint (spindle checkpoint)

Question 7

cyclin as major player in cell cycle

Answer 7

regulatory subunit

Constant cycle of synthesis and degradation during cell division

Activates Cdks and thereby help control progression from one stage of the cell cycle to the next

Question 8

Cdks (cyclin-dependent protein kinase) as major player in cell cycle

Answer 8

Dependent on cyclin

catalytic subunit

Enzyme that adds negatively charged phosphate groups to other molecules (phosphorylation), which indicates that the cell is ready to pass into the next stage of the cell cycle

Question 9

G1-Cdk

Answer 9

Cyclin D
Cdk4, Cdk6
Cln3
Cdk1

Question 10

G1/S-Cdk

Answer 10

Cyclin E
Cdk2
Cln1, 2
Cdk1

Question 11

S-Cdk

Answer 11

Cyclin A
Cdk2, Cdk1
Clb5, 6
Cdk1

Question 12

M-Cdk

Answer 12

Cyclin B
Cdk1
Clb1, 2, 3, 4
Cdk1

Question 13

Commit the cell to DNA replication (G1/S Transition)

Answer 13

Cdk4/6 + Cyclin D

Question 14

Help promote passage thru restriction point in late G1 (G1/S Transition)

Answer 14

R point (late G1): Cdk2 + Cyclin E

Question 15

Ensures DNA is copied once and only once (S Phase progression)

Answer 15

Cyclin A and Cdk2

Question 16

M-phase promoting factor (G2/M transition)

• Maturation promoting factor
• Promote the events of mitosis

Answer 16

Cdk1 (cdc2) + Cyclin B

Question 17

cyclin oscillates during the cycle

Question 18

phosphorylates an activating site in Cdks

Answer 18

Cdk-activating kinase (CAK)

Question 19

phosphorylates inhibitory sites in Cdks; primarily involved in controlling entry into mitosis

Answer 19

Wee1 kinase

Question 20

removes inhibitory phosphates from Cdks

Answer 20

Cdc25 phosphatase

Question 21

Phosphatases decrease when

Answer 21

cdk activity increases

Question 22

Dephosphorylates of Cdc25 and Wee1 during anaphase and telophase

Answer 22

Protein phosphatase 2 (PP2A)

Question 23

Cdk monitors a

Answer 23

cyclin, a protein kinase and a protein phosphatase

Question 24

Cdk inhibitory protein (CKIs)

Suppresses G1/S-Cdk and S-Cdk activities in G1

Helps cells to withdraw from cell cycle when they terminally differentiate

Answer 24

p27

Question 25

suppresses G1/S-Cdk and S-Cdk activities following DNA damage in G1; transcriptionally activated by p53

Answer 25

p21

Question 26

promotes transcription of genes that induce cell cycle arrest or apoptosis in response to DNA damage or other cell stress regulated by Mdm2

Answer 26

p53

Question 27

Is the addition of ubiquitin molecules residues of a protein directing the proteins for degradation via the proteasome or by lysosomes Involves ubiquitin ligases

Answer 27

Ubiquitination

Question 28

Catalyzes ubiquitylation of securin and S-cyclins and M-cyclins

Answer 28

APC/C (anaphase promoting complex or cyclosome)

Question 29

APC/C-activating subunit in all cells Triggers initial activation of APC/C at metaphase-to-anaphase transition, stimulated by M- Cdk activity

Answer 29

cdc20

Question 30

Binds into and inhibits the activity of separase

Answer 30

securin

Question 31

Cleave subunit of cohesin separating the sister chromatids

Answer 31

separase

Question 32

APC/C activating subunit that maintains APC/C activity after anaphase and throughout G1 Inhibited by Cdk activity

Answer 32

cdh1

Question 33

catalyzes ubiquitylation of regulatory proteins involved in G1 control, including CKIs

Answer 33

SCF (Skp, Cullin, F-box containing complex)

Question 34

three processes that determine cell size

Answer 34

cell growth, cell division, cell survival

Question 35

Stimulates cell division Triggers G1/S-Cdk activity that relieves negative controls of cell cycle

Answer 35

mitogen

Question 36

Stimulates cell growth (an increase in cell mass) by promoting the synthesis of proteins and other macromolecules

Answer 36

growth factors

Question 37

Promote cell survival by suppressing programmed cell death

Answer 37

survival factors

Question 38

Stimulate cells to divide, such as fibroblasts, smooth muscle cells and neuroglial cells

Answer 38

PLATELET-DERIVED GROWTH FACTOR (PDGF)

Question 39

Acts on epithelial and nonepithelial cells

Answer 39

EPIDERMAL GROWTH FACTOR (EGF)

Question 40

Induces the proliferation of red blood cells

Answer 40

ERYTHROPOIETIN

Question 41

Inhibits the proliferation of several cell by blocking cell-cycle progression

Answer 41

TRANSFORMING GROWTH FACTOR-ẞ (TGF- ẞ)

Question 42

high cell cycle regulators p15 p21 p27 p57

Answer 42

cell cycle arrest

Question 43

high ROS production

Answer 43

DNA damage

Question 44

low TERT

Answer 44

telomere shortening

Question 45

high PAI-1, ECM, ECM regulators, cytokine, chemokine

Answer 45

SASP, overall cellular senescence

Question 46

Family of proto-oncogenes and transcription factors promote cell cycle by increasing the expression of genes encoding G1-cyclins

Answer 46

Myc

Question 47

Genes that promotes transcription of genes required for G1/S progression Binds with Cdk and cyclin A producing the S-promoting factor

Answer 47

E2F

Question 48

Tumor suppressor protein that serve as a guardian of the restriction-point gate Prevents excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide

Answer 48

Retinoblastoma protein (Rb)

Question 49

pRB serves as a break in cell cycle by binding to E2F Inactivation (hyperphosphorylation) of pRb helps switch the progress of the cell cycle to mitosis Phosphorylation inactivates pRB since it cannot bind to E2F

Answer 49

pRB-E2F pathway

Question 50

quantitative colorimetric method to determine the cell proliferation. utilizes the yellow tetrazolium salt (3-(4,5-dimethylthiazo1-2-yl)-2,5-diphenyltetrazolium-bromide) which is metabolized by mitochondrial succinic dehydrogenase activity of proliferating cells to yield a purple formazan product by the mitochondria of viable cell

Answer 50

MTT assay