1. G1: the cell grows by producing more proteins and organelles
2. S: DNA replication occurs
3. G2: the cell prepares for cell division with the appearance of
centrosomes
4. M: mitosis and cytokinesis occurs
5. Some cells, like mature nerve cells or muscle cells, do not
divide. Other cells will divide only when the cellular
environment signals that it is necessary. What phase of the
cell cycle are these cells said to be in when they are not
dividing or planning to divide?: G0
6. Name the three checkpoints.: G1 , G2 , M
7. Indicate the phase of the cell cycle, and what part of the
phase (early or later), where each checkpoint occurs.: G1 -
later
G2 - later
M - later
8. The DNA has been completely replicated and checked for
errors.: G2 check- point
9. There is ample supply of energy and raw materials
available.: G1 and G2 checkpoint
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, 10. All chromosomes are attached to the spindles.: M
checkpoint
11. There is adequate room in the environment for more cells.:
G1 checkpoint
12. Which checkpoint appears to regulate whether the cell is in
G0 or not?: the
G1 checkpoint is the point in the cycle where the cell goes into or
out of G0.
13. Predict the result of a mutation that allows a cell to move
past checkpoint G1 even though the cell has not grown
sufficiently.: the daughter cell would be small and possibly not
able to store enough nutrients within the cell to survive.
14. Predict the result of a mutation that allows a cell to move
past checkpoint G2 even though the DNA replication has not
been completed.: the DNA in the daughter cells would not be
complete and the cells would not survive.
15. Predict the result of a mutation that allows a cell to move
past checkpoint M even though the chromosomes were not
prepared for division.: the chromo- somes might end up in the
wrong daughter cell. for example, one cell might get both copies of
a chromosomes while the other gets none.
16. Recall that the purpose of the kinases is to phosphorylate
other molecules, thus bringing them to a higher energy state.
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