Multiple Choice
Many of the negative regulator proteins of the cell cycle were discovered in what type of cells?
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11. Cell Division
Cell Cycle Regulation
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At which of the cell-cycle checkpoints do external forces have the greatest influence?
A
G1 checkpoint
B
M checkpoint
C
G2 checkpoint
D
S checkpoint
Verified step by step guidance1
Understand the role of cell-cycle checkpoints: These are control mechanisms in eukaryotic cells which ensure proper division of the cell. They help prevent errors during cell division.
Identify the G1 checkpoint: This is the first checkpoint in the cell cycle, occurring at the end of the G1 phase, before the cell enters the S phase. It is crucial for assessing the cell's size, nutrients, growth factors, and DNA integrity.
Recognize the influence of external forces: External signals, such as growth factors, have a significant impact at the G1 checkpoint. These signals can promote or inhibit the progression of the cell cycle.
Compare with other checkpoints: The G2 checkpoint checks for DNA damage after replication, and the M checkpoint ensures proper chromosome alignment before mitosis. These are more focused on internal cell conditions rather than external signals.
Conclude that the G1 checkpoint is where external forces have the greatest influence, as it is the point where the cell decides whether to proceed with division based on external growth signals.
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