Cell Cycle

Question 1

_ control transitions between phases of cell cycle. This process is regulated by _ and _ suppressors.

Answer 1

check points

cyclins dependent kinases and tumor suppressors

Question 2

_ phase the shortest phas eof the cell cycle includes mitosis and cytokinesis

Answer 2

M

Question 3

mitosis is broken down into?

Answer 3

Prophase, prometaphase, metphase, anaphase, and telomerase

Question 4

_ is of variable duration

Answer 4

G1

Question 5

cyclin-depedent kinaases are _ expressed but inactive when not bound to _

Answer 5

constituitively

cyclin

Question 6

cyclins are ?

Answer 6

phase specific regulatory proteins that CDKs

Question 7

cyline stimulate CDKs when

Answer 7

when they are stimulated by growth factors

Question 8

the cyclin-cdk comples can do what

Answer 8

phosphorylate other proteins to aid in cell cycle progression

Question 9

mutations in tumor suppressor genes can result in

Answer 9

unrestrained cell division (Li Fraumeni syndrome)

Question 10

growth factos bind _ _ _ to transition the cell from G1 to S phase

Answer 10

tyrosine kinase receptors

Question 11

what is a permenant cell type and what are some examples

Answer 11

these are cells that remain in G0 and regenerate from stem cells

example: neurons, skeletal muscle, cardiac muscle, RBCs

Question 12

what are stable cell and give examples

Answer 12

stable cells are those that enter G1 from G0 when stimulated

example: hepatocytes, lymphocytes, PCT, periosteal cells

Question 13

what are labile cells and give examples

Answer 13

cells that never go into G0 and divide rapidly and have a short G1

they are most affected by chemotherapy

examples: bone marrow, gut epithelium, skin, hair, germ cells

Question 14

what happens in prophase

Answer 14

chromosomes condense and spindle fibers form (made up of microtubules)

Question 15

what is prometaphase

Answer 15

chromosomes start to organize on mitotic spindle

Question 16

metaphase

Answer 16

chromosomes line up at metaphase plate

Question 17

anaphase

Answer 17

chromosomes seperate to opposite ends of the cell

Question 18

telophase

Answer 18

spindle breaks and and cell divides

Question 19

G1-S phase checkpoint is where the cell commits to growing: all checkpoints depend on?

Answer 19

CDKs

(cyclin depended kinases)

cyclin- regulatory proteins

Question 20

subtypes of cyclins

Answer 20

A-D

levels fluctuate through cell cycle phases

Question 21

during G1 phase CDK activity is _

_ activate CDK and entry into the S phase

Answer 21

suppressed

mitogens

Question 22

how do mitogens activate CDks

Answer 22

they interact with cell surface receptors, activate intracellular pathways and increase G1 cyclin levels resulting in an increase in CDK activity

Question 23

cyclin CDK complexes activate _ proteins

Answer 23

E2F

these are transcription factors that bind to DNA promoter regions and activate genes for S phase

Question 24

E2F is normally inhibited by?

Answer 24

Rb (retinoblastoma protein) when the cyclin-Cdk complexes phosphorylate E2F the inhbition by RB is lost

Rb is a tumor suppressor

Question 25

in the G1- S checkpoint _ damage allows for arrest in cell division, allowing for repoair and preventing the development of mutatant cells/cancer

Answer 25

damage

DNA damage initiates signaling pathways

Question 26

DNA damage in the G1 phase causes cells to enter what pathways?

Answer 26

ATM or ATR

Question 27

what is the ATM pathway

Answer 27

this is a pathway for double stranded DNA breaks

ATM= ataxia telangiectasia mutated

***ATM gene mutated leads to ataxia telangctasia

Question 28

what is the ATR pathway

Answer 28

pathway for single stranded DNA breaks

Question 29

ATM/ATR systems sensing DNA damage has a major target on?

what happens?

Answer 29

P53

P53 become phosphorylated, and stable, it induces P21 transcription. P21 will bind to CDK and inhibit progression through the cell cycle

both P53 and P21 are tumor suppressors

Question 30

retinoblastoma mutation

Answer 30

RB1 gene which codes for the Rb protein

this allows E2F to allow progression from G1-S in an unregulated fashion

eye malignacy in children

Question 31

what is Li-fraumeni syndrome

Answer 31

SBLA cancer syndrome
sarcomas, breast, leukemia, adrenal gland cancers at a young age

mutation in TP53 gene and not enough P53 which will allow for damaged DNA to accumulate and cause cancer.