lecture 15-17 (Regulation of Eukaryotic cell cycle control and cell division) Flashcards
when cells divide too quickly before reaching its optimum size the daughter cells will become:
too small to stay alive
when the cell grow too large before cell division this will cause:
an increase number of cells (improper function)
True or False: cells divide all the time
false, only when needed
an example of a cell that continuously divides:
cells lining the intestine
example of a cell that never divides:
nerve cells
how do cells communicate?
using signalling molecules which is induced by the cell receptor
what is the function of cell signal?
makes cells respond in different ways and makes it divide
when does a cell turn cancerous?
when the cell losses the comunication and divides without command
what is the function of signalling pathway?
regulate gene expression, Cytoskeletal organisation and metabolism
what are main events in cell cycle?
1) s-phase: chromosomes are duplicated (DNA)
2) M-phase: chromosomal distribution
what is the result of cell division before proper DNA replication?
one daughter cell will have less chromosomes
how does the cell control chromosome replication and segregation?
by check points that prevent the initiation of the following step unless the earlier step have been completed.
DNA replication is initiated when ____ is activiated
cdk2 & cyclin A
what is the function of cyclin D + cdk 4 & 6?
regulates Rb which inactivates the E2F by binding with
why is E2F important?
because it transcrip many genes required for G1, S, & M phase
what is the function of cyclin E and CDK 2?
Cyclin E/CDK2 phosphorylates retinoblastoma protein (Rb) to promote G1 progression.»_space;> activate postive feedback from E2F
when E2F is activated it produces which cyclin:
cyclin E
cyclin A
cyclin B
True or False: CDK are protein and cyclin are enzymes
false, cyclin are protein and CDK are enzymes
what is the relation between the activity of Rb and E2F transcription factor?
when Rb is activited it will inactive E2F but when Rb is phosphorlated it will inactive and active E2F transcription
what is the function of cdk inhibitors (p15/p16/p21/p27)?
it blocks the cell cycle progression from G1 to S phase
where does the cyclin and cdk of the s phase accumlate?
in the G1 phase
in G1 phase what happens to cdk 2 (s phase cdk)
it will bound to an inhibitor that will be destructed to initiate the s-phase
how does the inhibitors degrade?
it will be phosphorylated by cyclin E - CDK2 and degraded by proteasome
what is the name of the s-phase inhibitor in yeast?
Sic 1
True or False: the initiation factors cannot initiate when phosphorylated
TRUE
The activation of ———- causes the initiation factors to become unphosphorylated giving it function
cdc 14 phosphatase
__________ triggers degradation of cyclin B
APC/C-Cdh1
what is the function of CDC25 enzyme?
activate M-CDK by removing the inhibitory phosphates (cannot happen unless DNA replicates
which phase will the M phase-promoting factor (MPF) be activated?
at the end of S-phase
APC/C and cdc20 complex causes:
the degradation of securin and the release of separase to breakdown cohesion ring
APC/C and cdh1 complex causes:
the degradation of cyclin B to complete mitosis (M-phase)
what is the function of Mitotic cyclin and CDK:
phosphorylate many proteins to progress in mitosis
function of cdc 14
dephosphorylate all phosphorylated proteins in mitosis
______ and ________ are proteins that activates in the site of damage for repair.
ATM and ATR
cycling of MPF (mitosis) activity in Xenopus egg depends on:
the synthesis and degradation of cyclin B
