High School Biology : The Cell Cycle
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Example Questions
Example Question #31 : The Cell Cycle
Most cells spend the vast majority of their time in __________.
interphase
meiosis
mitosis
anaphase I
prophase
interphase
Most cells spend about 90% of their time in interphase. Note that mitosis and meiosis comprise only about 10% of the cell cycle.
Example Question #2 : Understanding Cell Cycle Regulation
During the G1 phase of the cell cycle, in which form will Eukaryotic DNA be found?
Chromatid
Chromatin
Plasmid
Unfolded continuous strand
Chromosomes
Chromatin
Chromosomes and Chromatid are both incorrect because eukaryotic DNA is condensed into these tightly packed chromosomal structures during M phase of mitosis. Plasmids are not found in eukaryotes and an unfolded continuous strand of DNA would be too long to fit within a nucleus. Thus, Chromatin is the correct answer choice; chromatin is a protein-DNA complex in a loosely packed form which allows for gene transcription which is necessary during the G1 phase of the cell cycle.
Example Question #3 : Understanding Cell Cycle Regulation
What is the initial checkpoint in a mammalian cell cycle whose major function is to allow or disallow a cell to mitotically divide?
G2 checkpoint
S checkpoint
G1 checkpoint
M checkpoint
G3 checkpoint
G1 checkpoint
The G1 Checkpoint is the correct answer, because if a cell gets a signal at this checkpoint then the cell goes on to complete the S, G2, and M phases and will end up dividing. If this signal is not received at the G1 checkpoint then the cell enters the non-dividing G0 phase.
Example Question #271 : Cell Biology
There are several checkpoints during the cell cycle to ensure proper growth and division. Which checkpoint of the cell cycle is considered the "point of no return?"
G1 checkpoint
Telophase checkpoint
Metaphase checkpoint
G2 checkpoint
There is no point of no return. The cell can always go back and resume normal cell function.
G1 checkpoint
Once the cell passes the G1 checkpoint, the cell becomes committed to the cell cycle and enters the S phase where DNA is replicated. The checkpoint is to ensure the cell has grown enough and has enough resources to begin DNA replication. The next checkpoint is the G2 checkpoint, where the cell checks and makes sure the DNA replicated correctly before beginning mitosis. If the cell does not pass this checkpoint, it commences apoptosis and dies.
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