FOM 7.3.1 Flashcards
What is the role of G1?
Cell growth, make stuff, longest phase, prevents prod of smaller daughter cells
What is the role of S?
DNA replication
What is the role of G2?
Checkpoints (The Accountant)
What is the role of M phase?
Separation of the cell into daughter cells (PMAT)
What are the three essential functions of cell cycle?
Propagation, Replace dead cells, Increase specific cell types
On which phase do mitogens act? Mitogens increase expression of what gene regulatory protein? What cyclin is up regulated as a result?
G1; Myc; Cyclin D
What are some characteristics of cells in the G1 phase?
Cell energy high, increased protein synthesis, some organelle duplication, increased cell size
What is sensed by mTOR? What does it initiate?
Nutrients (Branched core AA); protein synthesis
What is the inhibitor of mTOR?
Rabamycin
What is the catchy slogan for S phase?
Making more of a good thing
Pair ORC, MCM, Licensing factors, DNA pol α, DNA pol δ/ε, and clamping proteins with their corresponding phase.
Look at picture
Describe the western blot of CDC6, CDT1, and geminin.
Look at picture
What are the functions of cohesions?
Wraps around newly synthesized DNA (sister chromatids during S phase), acts as a cage, can’t go through M phase until cage is removed (broken down late in mitosis)
What are the phases of M phase?
PMAT (Prophase, Metaphase, Anaphase, Telophase) Hint: Pittsburg Made A Touchdown
Name the three positive and three negatives cell cycle regulators.
Pos: Cyclins, CDK, protein degradation Neg: Txn Repressors, CDKI, Check points
Where do cyclins get their name?
They are proteins that are expressed in cycles.
Make the chart that compares phase of cell cycle to Cyclins, CDK partner, and function.
Look at table
Describe the two positive feedback methods of an activated Cdk.
1) Phosphorylating a phosphatase (cdc25), which increases removal of an inhibitory phosphate group 2) Inhibiting the Cdk-inhibitory kinase
How does CDK1 initiate M phase? (4)
1) Assemble mitotic spindle 2) Chromosome condensation 3) Nuclear envelope breakdown 4) Actin cytoskeleton rearrangement
What are the three mechanisms for inactivating a Cdk?
1) inhibitory phosphorylation 2) inhibitory protein 3) no cyclin (Lauren, you should already know this!)
What are the two ubiquitin ligases of the cell cycle?
SCF and APC/C
Describe how the composition of ubiquitin ligases aids in their ability to alter their activity.
The ligases have four different protein portions (Catalytic, Scaffold, Adaptor, Variable Component), which allows for a mix-and-match system that can alter function of degradation
When is the SCF complex most active?
G1/S push cell through cell cycle
APC/C complex is the key regulator of which phase?
M phase tags cyclin and targets for proteosome
APC/C is also used in which process that is unique to M phase?
Sister chromatid seperation (APC/C marks securin for degradation, which allows separase to cleave the cohesion complex)
What is the role of mitogens?
Interact with surface receptor and MAPK cascade. Leads to activation of cyclin Ds which activate G1-CDK.
What is the role of mTOR?
It is involved in regulation of cell size by sensing nutrients. This also activates target proteins that push the cell through the cycle.
When are Cdc6 levels highest and lowest?
Cdc6 rises in G1 through S phase and is degraded in G2 to prevent multiple rounds of replication
When are cdt1 levels highest and lowest?
cdt1 is highest during G1 and is degraded during S phase
What does Geminin do?
It in an inhibitor of cdt1 and increases its levels in late S and G2 phase
What does cyclin D do?
It combines to made G1-CDK which promotes passage through G1 and inhibits Rb
What does Cyclin E do?
It combines to make G1/S-CDK which commits the cell to replicate DNA
What does cyclin A do?
It combines to make S-CDK which stimulates chromosonal duplication
What does cyclin B do?
It combines to make M-CDK which stimulates entry into M phase at the end of G2
What is the process of activation of CDK1?
Dephosphorylation of CDK1 by Cdc25 leads to activation of it to let it work on amplification process
What are some methods of CDK1 regulation?
Inhibiting phosphorylation, and degrading the cyclin or having none present
DNA damage leads to what ?
Activation of p53 which leads to increased Chk1 which leads to inactivation of CDK1 and arrest in cell growth in G2/M phase
What is the role of retinoblastoma?
It is inhibiting E2F in normal state and then is acted upon by cyclin D which has it get rid of HDACs, then the G1/S-CDK will act on it to separate the Rb from E2F leading to an active E2F.
Gaurdasil is 98% against HPV. It specifically fights off the HPV that have viral protein E7. What is so problematic about E7?
E7 binds to and leads to the degradation of Rb proteins (loss of the G1/S check point)
