Epithelium: Cell Cycle

Question 1

what is occuring at G1 cyclin wise

Answer 1

g1: Cdk6 and Cdk4 activated by cyclin D
activation of Cdk4 leads to the phosphorylation of Rb and to the release of TFs which activate cyclin A and E (early)

Cyclin E activates Cdk2 which gets G1 thru checkpoint into S

Question 2

what is happening at S cyclin wise

Answer 2

cyclin A activates cdk2 again which recruits DNA pol

Question 3

what is happening at G2 cyclin wise

Answer 3

cyling A also activates Cdk1 which triggers chromosomal conensation

Question 4

What happening during mitosis cyclin wise

Answer 4

cyclin B activates Cdk1

Question 5

What is the affect of phosphorylation on Rb?

Answer 5

Rb releases the TF it was attached too

Question 6

How many genes have to be affected for RB tumors to occur?

Answer 6

two

same as with williams tumor (WT-1) KIDNEY

Question 7

what is the most frequently mutated gene in regards to tumors?

Answer 7

p53

Question 8

how many subunits does p53 have? and how does it react to mutation?

Answer 8

four subunits
one mutation of a subunit kinda affects the others
(mild to strong reaction) vs RB which is all or nothing

Question 9

What is the longest phase of the cell cycle?

Answer 9

G1 11 HOURS

Question 10

How long is S phase of the cell cycle

Answer 10

8 hours

Question 11

how long is the G2 phase of the cell cycle

Answer 11

4 hours

Question 12

how long is mitosis?

Answer 12

1 hour

Question 13

what is the shortest phase of the cell cycle?

Answer 13

mitosis

Question 14

FACS

Answer 14

flourence activated sorter
measures DNA content ( c value)
2c at end of g1
4c at end of s
4c at end of g2

Question 15

when does the nuclear lamina diassemble

Answer 15

at the end of prophase with the diassembly of the nuclear envelope

Question 16

Describe the nuclear lamina at prophase

Answer 16

at prophase PKC and cyclin A(activates Ck1)

phosphorylates lamins leads to disassembly of nuclear lamina

Question 17

describe the nuclear lamina at anaphase

Answer 17

nucleoporins+lamina association polypetide 2beta+lamina B receptor+emerin

Question 18

nuclear lamina at telophase

Answer 18

attach tot he surface of the chromosomes +cisternae (ER) recruited by nuclear porins then rebuild

final step is the desphosphorylation of laminB my protein phosphatase !

Question 19

Describe what happens during prophase

Answer 19

centrosomes separate
mitotic spindle starts
sister chromatids together (cohesin)
chromatin packed (codensin)
nucleolus disappears

Question 20

describe what happens during prometaphase

Answer 20

nuclear envelope completly diassembled

chromosomes form kinetochores at centromere

Question 21

metaphase

Answer 21

microtubules attach to chromosomes
chromosomes align at plate
APC

Question 22

APC

Answer 22

anaphase promoting complex
diassembles when kinetcore microtubules attach to kenetochore
if they dont attach then APC stops mitotic cycle by delaying cyclin activity

Question 23

Anaphase

Answer 23

sister chromatids separate
TOPOISEMERASE-(kinetechore region) enzyme which frees entangled chromatin
a. kinetechore microtubules shorten
b/ polar microtubules lengthen
ANEUPLOIDY OCCURS HERE

Question 24

Telophase

Answer 24

nuclear envelop reforms
nuclear lamina reassemble
chromosome decondense becomes chromatin
nucleolus reappear

Question 25

telomerase

Answer 25

protects length of telomere
not in somatic cells
has reverse transcriptase activity

Question 26

telomere

Answer 26

maintain chromosome integrity (decreases in length with each cycle)
ends of chromosomes (repeated nucleotide seq)
TTAGGG

Question 27

senescence

Answer 27

when telomeres shorten to a pt where chromosomes integrity cant be maintained

Question 28

relationship of tumors and telomerase

Answer 28

tumor high levels of telomerase

Question 29

Telemerase complex

Answer 29

telomerase reverse transcriptase +

template RNA + dyskerin (DKC1)

Question 30

How does the telomerase complex get to telomere?

Answer 30

through the TCAB1

reassemble at chromosome with pontin and reptin to help (ATPases)

Question 31

Where is the telomerase complex made?

Answer 31

cajal bodies in the nucleus

Question 32

issue with telomere

Answer 32

dyskeratosis congenita

Question 33

When Mdm2 is inactivated what is the state of P53

Answer 33

activated …leads to tumor suppression