Cell Cycle Flashcards
What are the three major checkpoints?
G1/S checkpoint (restriction point), checks for replication signals, nutrients, and space; G2/M checkpoint, checks for DNA replication; and metaphase/anaphase checkpoint, checks for chromatid attachment by MT
What occurs in G1?
The cell is growing but not dividing.
What occurs in S?
DNA and MTOC replication.
What occurs in G2?
Cell is waiting for mitosis signal.
What occurs in prophase?
Histone H1 condenses chromosomes and MTOCs move to the poles
What occurs in prometaphase?
Nuclear envelope breakdown and MT fishing for kinetochores.
What occurs in metaphase?
Chromosomes line up
What makes the cell proceed to anaphase?
Anaphase promoting complex
What occurs in anaphase?
Sister chromatids separate and cohesin degrades
What occurs in telophase?
Chromosomes decondense and nuclear envelope reforms
What occurs in cytokinesis?
MF network pinches cell in half at metaphase plate with myosin bipolar motor.
How does GEF affect cytokinesis?
It activates Rho which cascades to Rho-dep kinase, rMLC-P, and contracts cell.
How does GAP affect cytokinesis?
GAP inhibits Rho which decreases Rho-dep kinase, rMLC-P, and stops cytokinesis.
What is the function of Cdc25?
It drives cell division
What is the function of Wee-1?
It slows cell division
Where in the cell cycle are Cdc25 and Wee-1 found and what do they regulate?
At the G2/M checkpoint and they regulate maturation promoting factor.
What is MPF?
It is a CDK/cyclin dimer that causes cell maturation
How does a CDK/cyclin dimer become activated?
Inactivating phosphate from ATP is added to dimer by Wee-1, then an activating phosphate is added by CAK, Cdc25 cleaves inactivating phosphate so CDK/cyclin is activated.
What is the function of MAD/Bub?
It inactivates APC at the metaphase/anaphase transition and stops when all kinetochores are attached to MT
What does APC do?
It allows for sister chromatid separation by tagging securin for degradation.
