Flashcards in Epithelium: Cell Cycle Deck (33):
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
what is happening at S cyclin wise
cyclin A activates cdk2 again which recruits DNA pol
what is happening at G2 cyclin wise
cyling A also activates Cdk1 which triggers chromosomal conensation
What happening during mitosis cyclin wise
cyclin B activates Cdk1
What is the affect of phosphorylation on Rb?
Rb releases the TF it was attached too
How many genes have to be affected for RB tumors to occur?
same as with williams tumor (WT-1) KIDNEY
what is the most frequently mutated gene in regards to tumors?
how many subunits does p53 have? and how does it react to mutation?
one mutation of a subunit kinda affects the others
(mild to strong reaction) vs RB which is all or nothing
What is the longest phase of the cell cycle?
G1 11 HOURS
How long is S phase of the cell cycle
how long is the G2 phase of the cell cycle
how long is mitosis?
what is the shortest phase of the cell cycle?
flourence activated sorter
measures DNA content ( c value)
2c at end of g1
4c at end of s
4c at end of g2
when does the nuclear lamina diassemble
at the end of prophase with the diassembly of the nuclear envelope
Describe the nuclear lamina at prophase
at prophase PKC and cyclin A(activates Ck1)
phosphorylates lamins leads to disassembly of nuclear lamina
describe the nuclear lamina at anaphase
nucleoporins+lamina association polypetide 2beta+lamina B receptor+emerin
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 !
Describe what happens during prophase
mitotic spindle starts
sister chromatids together (cohesin)
chromatin packed (codensin)
describe what happens during prometaphase
nuclear envelope completly diassembled
chromosomes form kinetochores at centromere
microtubules attach to chromosomes
chromosomes align at plate
anaphase promoting complex
diassembles when kinetcore microtubules attach to kenetochore
if they dont attach then APC stops mitotic cycle by delaying cyclin activity
sister chromatids separate
TOPOISEMERASE-(kinetechore region) enzyme which frees entangled chromatin
a. kinetechore microtubules shorten
b/ polar microtubules lengthen
ANEUPLOIDY OCCURS HERE
nuclear envelop reforms
nuclear lamina reassemble
chromosome decondense becomes chromatin
protects length of telomere
not in somatic cells
has reverse transcriptase activity
maintain chromosome integrity (decreases in length with each cycle)
ends of chromosomes (repeated nucleotide seq)
when telomeres shorten to a pt where chromosomes integrity cant be maintained
relationship of tumors and telomerase
tumor high levels of telomerase
telomerase reverse transcriptase +
template RNA + dyskerin (DKC1)
How does the telomerase complex get to telomere?
through the TCAB1
reassemble at chromosome with pontin and reptin to help (ATPases)
Where is the telomerase complex made?
cajal bodies in the nucleus
issue with telomere