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BIOL 410 - Section 2
Terms in this set (28)
CDKs need to bind to what other protein for their activity?
Ubiquitination of proteins can lead to
Either modified activity or localization of the target protein or degradation by the proteasome, depending on how the ubiquitin is attached
The "point of no return" in the cell cycle is
The G1 restriction point
Which cyclin-CDK complex is important for initiating S phase?
The CDK inhibitor p16 is important at what stage of the cell cycle?
G1 (inhibits CDK4/6)
Why is the cell cycle unidirectional? For example, if something goes wrong at the beginning of S phase, why can't a cell stop and go back to G0?
The cyclins prevent it from being able to go backwards- the necessary cyclins aren't present anymore
The major protein that inhibits entry into S phase is
Which of these is a mechanism by which Rb inhibits entry into S phase?
Recruiting HDACs to E2F-responsive promoters
CDC25 is a phosphatase that is required for entry into M phase. What is its principle target for dephosphorylation?
What happens in the cell goes ahead and divides even though not all chromatids are attached to spindles?
One of the two daughter cells will inherit too many chromosomes, the other will have less than normal (aneuploidy-characteristic of solid tumors)
What is the role of securin in the M phase checkpoint?
A consequence of a failure of the M checkpoint is
Premature anaphase, failure to separate all of the sister chromatids, aneuploidy, daughter cells inherit the wrong number of chromosomes
The drug Taxol inhibits cell division by
Preventing growth and retraction of microtubules
Cells that are in G1
are preparing to enter S phase
One of the most important ways that growth factors stimulate cells to enter G1 is by
stimulating expression of cyclin D
The checkpoint that ensures that the cell's DNA is completely replicated is in
What is aneuploidy?
Having either too many or too few copies of a chromosome
The CDC25 protein
is important for release from the G2 checkpoint, is a phosphatase, activates cdk1, is inhibited by kinases that sense DNA damage
Which of these are thought to be a mechanism used by mutant p53 to transform cells?
Binding to wild type p53 and preventing it from functioning properly
Cervical cancers usually have wild type P53. This is because
almost all cervical cancer is caused by HPV infection, and HPV inhibits P53
Germline (inherited) inactivating mutations in the Rb gene are mainly associated with
In unstressed cells, the P53 protein is at __________ levels and functions as a tumor suppressor by ___________
low; inducing expression of antioxidant genes
Decreased Myc expression would tend to promote p53-dependent
cell cycle arrest
Select all statements that are correct
In familial retinoblastoma, only one additional Rb mutation is required in a retinoblast cell to develop retinoblastoma. Chances of this happening are high
The p53 protein is a
One of the ways that the P53 protein induces cell cycle arrest is by
activating transcription of CDK inhibitors
Which would be a dominant negative mutation?
A point mutation in the activation domain of a transcription factor that prevents it from binding to RNA polymerase, but doesn't prevent it from binding to DNA; A mutation in the DNA binding domain of P53, preventing it from binding to DNA but not preventing tatramerization
Under normal conditions, P53 levels are low because of ubiquitination by MDM2. When cells are stressed, P53 levels rise because
P53 gets phosphorylated, preventing interaction with MDM2
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