Cell Cycle Flashcards
How many cells of humans have?
around 37 trillion
How many different cells do humans have?
around 200
How many cell divisions occur every day?
around 2 trillion
Out of the 2 trillion cell divisions that occur daily, are they distributed evenly?
no
What is the lifespan of oesophagus lining cells and can they divide?
2-3 days, can divide
What is the lifespan of small intestine lining cells and can they divide?
1-2 days, can divide
What is the lifespan of large intestine lining cells and can they divide?
6 days, can divide
What is the lifespan of red blood cells and can they divide?
less than 120 days, cannot divide
What is the lifespan of white blood cells and can they divide?
10 hours-decades, cannot divide
What is the lifespan of smooth muscle cells and can they divide?
long-lived, can divide
What is the lifespan of cardiac muscle cells and can they divide?
long-lived, cannot divide
What is the lifespan of skeletal muscle cells and can they divide?
long-lived, cannot divide
What is the lifespan of neuronal cells and can they divide?
long-lived, most do not divide
Who discovered cyclin?
Tim Hunt
Who discovered cDC2?
Paul Nurse and Dr Hartwell
What happens in G1 phase of the cell cycle?
- cellular contents are duplicated, excluding chromosomes
- some cells exit via G0 phase and never multiply again
Which phase do most cells spend most their life in?
G1
What cellular contents are not duplicated during G1 phase?
chromosomes
What proteins are involved in G1 phase?
- cyclin D, E, A2 & B
- CDK 4, 6, 2 & 1
- pRB
- E2F
What is the major checkpoint for the transition into S phase?
G1 / S cyclin
no cyclin -> _____ CDK -> S phase factors _____
no cyclin means inactive CDK so S phase factors are ‘off’
+G1/S cyclin -> CDK is _____ -> G1/S targets are _____
presence of G1/S cyclin means CDK is activated so G1/S targets are phosphorylated
When G1/S targets are phosphorylated, what happens?
DNA replication enzymes are activated and S phase begins
Why are the G1/S targets phosphorylated?
?
