Cell Division Flashcards
what is the cell cycle critically controlled by?
cdk - cyclin-dependent kinases
when is cdk activity at its peak?
during mitosis
what is cdk regulated by?
+ phosphorylation
+ dephosphorylation
which cdk complex controls events in S phase of cell division?
active S-cdk
which cdk complex controls events in M phase of cell division?
cdk1 = cdc2
which cdk complex controls events during G1 phase of cell division?
cdk4/6
which cdk complex controls events between R point of G1 and start of S phase of cell division?
cdk2
which cdk complex controls events from start to middle of S phase of cell division?
cdk2
which cdk complex controls events from mid S phase M to end of G2 phase of cell division?
cdk1 = cdc2
how many checkpoints are there in G1?
- damaged DNA
2. unfavourable extracellular environment
how many checkpoints are there in S phase?
- damaged or incompletely replicated DNA
how many checkpoints are there in G2?
- damaged or incompletely replicated DNA
how many checkpoints are there in M phase
- chromosome improperly attached to mitotic spindle
when is the checkpoint for growth or quiescence?
R-Point (G1/S transition)
what disease can defects in cohesion cause?
Roberts Syndrome
- very rare
how are sister chromatids held together?
cohesion complex/rings made of cohesin
what do defects at spindle checkpoint cause?
aneuploidy
which cyclin controls events in M phase of cell division?
cyclin B
which cyclin controls events during G1 phase of cell division?
cyclin D
which cyclin controls events between R point of G1 and start of S phase of cell division?
cyclin E
which cyclin controls events from start to middle of S phase of cell division?
cyclin A
which cyclin controls events from mid S phase to end of G2 phase of cell division?
cyclin A
what is the role of p53 in DNA damage?
directs transcription of cdk-inhibitors
what is CHK2 activated by?
DNA damage
what is the role of CHK2?
inhibits cdc25
what are the stages of mitosis?
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
- cytokinesis
In metaphase, what must first happen for mitosis to proceed?
chromosomes are properly attached and under tension
what checkpoint occurs during metaphase?
spindle checkpoint
what occurs during prophase?
chromosomes become visible as paired chromatids and the nuclear envelope disappears
what happens during prometaphase?
phosphorylation of nuclear pore proteins and lamins by M-CDK causes the nuclear membrane to break down into numerous small vesicles. As a result, the spindle microtubules now have direct access to the genetic material of the cell
