Epithelium: Cell Cycle Flashcards Preview

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Flashcards in Epithelium: Cell Cycle Deck (33):
1

what is occuring at G1 cyclin wise

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

2

what is happening at S cyclin wise

cyclin A activates cdk2 again which recruits DNA pol

3

what is happening at G2 cyclin wise

cyling A also activates Cdk1 which triggers chromosomal conensation

4

What happening during mitosis cyclin wise

cyclin B activates Cdk1

5

What is the affect of phosphorylation on Rb?

Rb releases the TF it was attached too

6

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

two
same as with williams tumor (WT-1) KIDNEY

7

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

p53

8

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

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

9

What is the longest phase of the cell cycle?

G1 11 HOURS

10

How long is S phase of the cell cycle

8 hours

11

how long is the G2 phase of the cell cycle

4 hours

12

how long is mitosis?

1 hour

13

what is the shortest phase of the cell cycle?

mitosis

14

FACS

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

15

when does the nuclear lamina diassemble

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

16

Describe the nuclear lamina at prophase

at prophase PKC and cyclin A(activates Ck1)
phosphorylates lamins leads to disassembly of nuclear lamina

17

describe the nuclear lamina at anaphase

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

18

nuclear lamina at telophase

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 !

19

Describe what happens during prophase

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

20

describe what happens during prometaphase

nuclear envelope completly diassembled
chromosomes form kinetochores at centromere

21

metaphase

microtubules attach to chromosomes
chromosomes align at plate
APC

22

APC

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

23

Anaphase

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

24

Telophase

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

25

telomerase

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

26

telomere

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

27

senescence

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

28

relationship of tumors and telomerase

tumor high levels of telomerase

29

Telemerase complex

telomerase reverse transcriptase +
template RNA + dyskerin (DKC1)

30

How does the telomerase complex get to telomere?

through the TCAB1
reassemble at chromosome with pontin and reptin to help (ATPases)

31

Where is the telomerase complex made?

cajal bodies in the nucleus

32

issue with telomere

dyskeratosis congenita

33

When Mdm2 is inactivated what is the state of P53

activated ...leads to tumor suppression