Cell Bicycle Flashcards
What are the four phases of the cell cycle?
M cycle, G1 phase, S Phase, and G2 Phase
Are yeast cells haploid or diploid?
Haploid
What is purifying selection?
A very important sequence that stays in nearly all organisms
What do cdc2 mutant yeast do? What is it caused by?
cdc2 mutant yeast replicate way too much and it is caused by losing the gene altogether
What happens when the cdc2 gene is restored in the mutants?
Restores the genotype
What happens when human cdc2 is put into mutant cdc2 yeast?
Genome is STILL restored (cus amino acids are basically the same)
At what rate is cyclin synthesized in the cell?
Constant, always being made
What regulates Cdk activity?
Cyclin
What triggers M-phase?
Cyclic protein synthesis
What triggers G1?
Cyclin degradation
How does ubiquitin mediated protein degradation work?
Ubiquitin grabs on to cyclin -> puts it in a proteasome -> leaves proteasome -> cyclin is degraded
What catalyzes ubiquitin?
Ubiquitin ligase
What triggers the end of M-phase/cause entry into G1?
Ubiquitylation and degradation of cyclin
What does Wee1 do to Cdk?
Phosphorylates it to inactivate it
What does cdc25 do to Cdk?
Removes inhibitory phosphates from Cdk to activate it
What happens when Cdk is active and attached to a cyclin?
Cell division
If a cell is not ready to continue to the next stage of the cell cycle, what is activated?
Wee1
If a cell IS ready to move onto the next step of the cell cycle what does it activate?
Cdc2
What holds two chromosomes together during pre S phase?
Cohesion proteins