Chapter 5 Flashcards
What are the 4 phases of cell division?
G1, S, G2 and M
What is the goal of G1?
Prepare for DNA synthesis (growth phase). Accumulate ingredients for DNA synthesis
What is the goal of S-phase?
DNA replication
What is the goal of G2?
Prepare for mitosis?
What is the M-phase?
Mitosis
What is the difference between G2 and Prometaphase of Mitosis?
Cyclin B1 - CDK1 complexes are inactive in G2 and all of them are active in prometaphase.
When do the sister chromatids get separated?
During Anaphase
What are the subphases of mitosis?
Prophase, prometaphase, metaphase, anaphase, telophase
When is Cyclin D the most active?
In the beginning, but it keeps being active during the whole cell division cycle
When is Cyclin E the most active?
During transition from G1 to S-phase
When is Cyclin A the most active?
During the G2-phase
When is Cyclin B the most active?
During transition from G2 to M-phase
Which proteins inhibit Cyclin D?
The INK proteins (p16, p15, p18, p19)
Which proteins inhibit other cyclins than Cyclin D
p57, p27 and p21
What cyclin does CDK4 bind to?
Cyclin D
What cyclin does CDK2 bind to?
Cyclin E and Cyclin A
What cyclin does CDK1 bind to?
Cyclin B1
What protein target genes does RB protein repress?
E2F target genes
Which cyclin is activated through extracellular stimuli?
Cyclin D
What does the Cyclin D/CDK4 comples do with RB?
It phosphorylates RB and inactivates it
What does the inactivation of RB lead to?
Inactivation of RB ends the inhibition of E2f transcription factor, which then enables the production of Cyclin E. Cyclin E then phosphorylates RB even more and more Cyclin E is produced. The high amount of Cyclin E signals the transition from G1 to S-phase
How does p53 inhibit cyclins?
p53 activates p21, which then binds to the cyclin/cdk complexes and inhibits them, leading to cell cycle arrest
What does p16 inhibit?
p16 prevents the binding of cdk to cyclins by binding to cdk
What does Flavopiridol do?
It inhibits cyclin/cdk function in various cell phases.
In what phase are the chromosome checked for DNA damage?
In the G1 phase, after the DNA strands have been replicated
What kind of cell cycle control is lost during carcinogenesis?
Mostly loss of G1 control, but sometimes G2 control
What important control protein is lost in most tumors?
p53
