The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

Most cells spend about 90% of their time in interphase. Note that mitosis and meiosis comprise only about 10% of the cell cycle.

During mitosis, the metaphase checkpoint ensures that each duplicated chromatid is attached to the spindle apparatus. If the metaphase checkpoint is not satisfied, the cell will not enter anaphase. This checkpoint is essential for preventing aneuploidy, a condition in which there are an abnormal number of chromosomes in a cell.

The G1 checkpoint determines if the cell will enter the S phase to replicate DNA and prepare for cell division. Quiescent cells, cells that do not frequently divide, are often stopped at the G1 checkpoint for long periods. The G2 checkpoint is used to prevent the cell from entering mitosis if there were errors in the replication of DNA during the S phase. Failure to pass the G2 checkpoint can result in apoptosis. There is no G0 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.

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.

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.

Most cells spend about 90% of their time in interphase. Note that mitosis and meiosis comprise only about 10% of the cell cycle.

During mitosis, the metaphase checkpoint ensures that each duplicated chromatid is attached to the spindle apparatus. If the metaphase checkpoint is not satisfied, the cell will not enter anaphase. This checkpoint is essential for preventing aneuploidy, a condition in which there are an abnormal number of chromosomes in a cell.

The G1 checkpoint determines if the cell will enter the S phase to replicate DNA and prepare for cell division. Quiescent cells, cells that do not frequently divide, are often stopped at the G1 checkpoint for long periods. The G2 checkpoint is used to prevent the cell from entering mitosis if there were errors in the replication of DNA during the S phase. Failure to pass the G2 checkpoint can result in apoptosis. There is no G0 checkpoint.

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.