CELL CYCLE REGULATORS
II. Fill in the blank using the correct option from the word bank, be aware that
not all the words from the word bank will be used (make sure to highlight
your answer).
Word bank:
p53, cyclinA, ATM, 24, Chk1, tubulin, ATR, 72, Chk2, p21, cdk1, cyclinB, 36, MPF.
A. In mammalian cells, the cell cycle takes approximately ____ hours.
B. In the presence of DNA damage, the protein kinases known as ____ and ____
recognize the damage and then phosphorylate ____ and ____
respectively. This results in an increase in the levels of the tumor
suppressor protein known as ____, which then enters the nucleus and
behaves as a transcription factor to promote the transcription and
subsequent translation of the cell cycle regulator protein ____. This protein
will inhibit cell cycle progression by blocking $cdk/cyclin$ interactions.
III. Highlight the correct answer
A. Activation of a checkpoint means the cells get stuck in the phase where the
checkpoint was activated.
1. true
2. False
B. At what stage of the cell cycle will cells get stuck in the absence of serum?
1. G1
2. S
3. G2
4. M
5. There is no effect on the cell cycle.
