L1 Cell Cycle Flashcards
What causes cells to proliferate
extrinsic factors
Wha† can extracellular signals induce
post-mitotic, differentiated state, no proliferation
Which state of cell cycle is quiescence
G0
Is G0 reversible
yes
Proliferation
cell cycle growth and division
Quiescence
non-proliferative state imposed on cell
What drives the cell cycle
cyclins fluctuation
What is the function of cyclin/Cdk complex
activate or repress target genes
What is highly conserved throughout evolution?
Cyclins/cdks
What cyclin is associated with G1
Cyclin D & E
What cyclin is associated with S phase
Cyclin A
What cyclin is associated with M phase (mitosis)
Cyclin B
What cdk forms a complex with cyclin D
cdk4 and cdk6
What cdk forms a complex with cyclin E
cdk2
What cdk forms a complex with cyclin A
cdk2 and cdk1
What cdk forms a complex with cyclin B
cdk1
What is the cyclin equivalent in yeast
cln or clb
What are the two major control factors of the cell cycle?
different cyclins, checkpoints
Affect of DNA damage on cell cycle
causes cell cycle arrest
Describe cyclin E levels
low through G1, rapid increase after R point
Describe cyclin A levels
levels increase as cell enters S phase
Describe cyclin B levels
levels increase before mitosis
What causes cyclin level fluctuation
degradation of proteins
Degradation of cyclins
ubiquitination dependant
What are D type cyclins controlled by
extracellular signals - growth factors & integrin mediated ECM attachment
Effect of growth factor removal
collapse of cyclin D1 levels
What signals do cyclin Ds relay
messages from extracellular environment to cell cycle clock in nucleus
What are other cyclins levels controlled by
intracellular signals, cell cycle advance
Which phases of the cell cycle are autonomous
after restriction point in G1
Cdk inhibitor
CKI
What are the checkpoints in the cell cycle
G1 checkpoint, G2-M checkpoint, metaphase checkpoint
Effect of hyper-phosphorylation of E2F
commits cell to cell cycle
What are the 3 places where DNA damage is detected
G1, entry to S phase, entry into mitosis
DNA repair in G1
non-homologous end joining
DNA repair in G2
homologous recombination
What targets proteins for degradation
p53 bound to mdm2
What associates with the site of DNA damage
ATM/ATR
What renders the G1/s-cdk and S-cdk complexes inactive
p21
What prevents cell cycle progression
p21
What is different between embryonic cells and adult cells
embryonic cells undergo apoptosis rather than repair
What makes the cell become quiescent or grow
extracellular signals
What accompanies formation of most types of cancer
deregulation of R checkpoint
When is DNA replication
S phase
How often is DNA replicated
ONCE
What is licensing?
loading of inactive helicases onto replication origins
When does licensing occur?
G1
How often does licensing occur
once per cell cycle
Effect of forks stalling on DNA
DNA damage
What is different in the cyclin levels of embryos
Cyclin E and A maintain high levels throughout the cell cycle
What is different about the cell cycle in embryos
very short G1 phase