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Cell Cycle
N/A
46
Biology
Undergraduate 3
04/27/2012

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Term
Adults have around ... different cell types.
Definition
300
Term
Eg. of cells that divide constantly...
Definition
Blood, skin, intestinal lining
Term
Eg. of cells that don't normally divide, but can to replace lost cells
Definition
Liver
Term
Eg. of cells that divide in response to signal...
Definition
Immune cells
Term
Eg. of cells that never divide...
Definition
Neurons
Term
Is cell division highly regulated?
Definition
YES!
Term
What is the purpose of keeping cell division in check?
Definition
It allows us to maintain a reasonably constant size and shape throughout our lives.
Term
What is cancer in short?
Definition
Inappropriate cell division.
Term
Where is cancer rare and were is it common?
Definition
Rare in children; common in adults.
Term
Do tissues vary in their susceptibility to cancer?
Definition
YES!
Term
What are the stages of the cell cycle?
Definition
Mitosis, G1, S1, G2, Mitosis etc.
Term
What happens in G1?
Definition
Cell grows in size, prepares for DNA replication.
Term
What happens in S1?
Definition
DNA replication.
Term
What happens in G2?
Definition
Cell prepares for division (mitosis).
Term
What organism is a major tool in studying cell cycle regulation?
Definition
Budding yeast
Term
Why is budding yeast so good for studying cell cycle regulation?
Definition
Because you can look at them and see in what stage cycle they are at.
Term
T or F. All proteins can be denatured by excessive heat.
Definition
T
Term
What is the restrictive temperature?
Definition
36 degrees Celsius.
Term
What is the permissive temperature?
Definition
22 degrees Celsius.
Term
What do temperature-sensitive mutations do?
Definition
They change the protein so that it is inactive at restrictive temperatures and active at permissive temperatures.
Term
At what temperatures are cells wild type and mutant?
Definition
Wild type - 22. Mutant - 36.
Term
How do you screen for cell division mutants?
Definition
- haploid cells are treated with a mutagen.
- dilute and spread single cells on nutrient plate at 22 degrees.
- allow cells to grow into colonies.
- imprint colonies into 2 plates.
- grow one of them 22 and the other at 36.
- see which one has the missing colony to determine where the temperature-sensitive mutant is at.
Term
Mutations in different genes result in ...
Definition
... arrest at different points in the cell cycle.
Term
What are CDKs and DCDs?
Definition
Cyclin dependent protein kinases.
Term
What do kinases do?
Definition
They regulate the activity of other proteins by phosphorylation.
Term
What are the roles of cyclins?
Definition
- target the CDks to particular substrates.
- are specificity factors.
Term
T or F. Human cells will work in yeast and vice-versa.
Definition
T.
Term
What happens to the nuclear envelope during mitosis?
Definition
It breaks down.
Term
What is nuclear lamin?
Definition
It is an insoluble protein network that provides structure for the nuclear envelope.
Term
What happens in G1 in terms of Rb and E2F?
Definition
Unphosphorylated Rb inhibits E2F.
Term
What is E2F requires for?
Definition
DNA replication.
Term
T or F: Cyclin turns over between phases.
Definition
T.
Term
What happens G2 -> M in terms of controlling the transition?
Definition
- CDC2 is kept inactive by kinase until Mitosis.
- Then it is activated by a phosphatase.
- one CDC interacts with many cyclins.
Term
T or F. Cells don't blindly go through the cell cycle.
Definition
T.
Term
What is the role of the checkpoints?
Definition
Cells can stop and make repairs if there are problems.
Term
What is p53?
Definition
A transcription factor.
Term
What activated p53?
Definition
UV or radiation.
Term
What does p53 do?
Definition
Can stop the cell cycle before DNA synthesis.
Term
What happens if the damage can't be repaired?
Definition
p53 can induce programmed cell death.
Term
T or F. There is no checkpoint in mitosis.
Definition
F.
Term
T or F. Checkpoints ensure genome stability.
Definition
T.
Term
What does the human growth hormone have to do with regulating division?
Definition
- it's an external factor.
- thyroid stimulating hormone signals the thyroid.
- this increases the production of thyroxine.
- this increases the metabolic rate --> human growth hormone.
Term
What is signal transduction?
Definition
- a basic set up for producing an intracellular response from an extracellular signal.
Term
RAS is inactive when bound to...
Definition
GDP.
Term
RAS is active when bound to...
Definition
GTP.
Term
When a growth factor attaches to the receptor, RAS ...
Definition
becomes active (by binding to GTP) --> proliferation.
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