The cell cycle is made up of four main phases with sub-phases inside the main parts of the cycle.
The first main phase in the cell cycle is G0. G0 is a time in which the cell is resting and has stopped dividing.
When the cell is given the signal to reproduce or split the cell cycle starts interphase. G1, S, and G2 are the sub-phases of the part of the cell cycle called interphase. G1 is a time when the cell is growing or getting bigger and is starting to replicate its organelles. The G1 phase also has a checkpoint which makes sure everything is ready for DNA synthesis. The next step that happens in interphase is the S phase. While in the S phase DNA synthesis, or the replication of DNA, takes place. Following the S phase, G2 begins. G2 is a time in interphase where the cell continues to grow and makes sure that everything is ready for the M phase, also known as mitosis. If something in the G2 checkpoint is wrong the cell will either fix the problem or self-destruct.
Finally the cell is ready for mitosis. Mitosis is the the process of cell division when the nucleus divides, which happens in 4 steps. First comes prophase. While in prophase, chromatin condense, the nuclear membrane dissolves, and the spindle apparatus forms from the centrioles at opposite poles of the nucleus. The next phase of mitosis is called metaphase. While in metaphase the chromosomes line up in the center of the nucleus with the spindles connected to them. Anaphase comes next and at this point in mitosis the sister chromatids split and move to opposite ends of the cell. Finally to finish up mitosis the cell moves into what we call telophase. In Telophase the chromatin uncoil (uncondense), the nuclear membrane reforms and the spindle apparatus disappears. Then the final main phase of the cell cycle takes place. The cell splits in a process called cytokinesis.
When the cell is given the signal to reproduce or split the cell cycle starts interphase. G1, S, and G2 are the sub-phases of the part of the cell cycle called interphase. G1 is a time when the cell is growing or getting bigger and is starting to replicate its organelles. The G1 phase also has a checkpoint which makes sure everything is ready for DNA synthesis. The next step that happens in interphase is the S phase. While in the S phase DNA synthesis, or the replication of DNA, takes place. Following the S phase, G2 begins. G2 is a time in interphase where the cell continues to grow and makes sure that everything is ready for the M phase, also known as mitosis. If something in the G2 checkpoint is wrong the cell will either fix the problem or self-destruct.
Finally the cell is ready for mitosis. Mitosis is the the process of cell division when the nucleus divides, which happens in 4 steps. First comes prophase. While in prophase, chromatin condense, the nuclear membrane dissolves, and the spindle apparatus forms from the centrioles at opposite poles of the nucleus. The next phase of mitosis is called metaphase. While in metaphase the chromosomes line up in the center of the nucleus with the spindles connected to them. Anaphase comes next and at this point in mitosis the sister chromatids split and move to opposite ends of the cell. Finally to finish up mitosis the cell moves into what we call telophase. In Telophase the chromatin uncoil (uncondense), the nuclear membrane reforms and the spindle apparatus disappears. Then the final main phase of the cell cycle takes place. The cell splits in a process called cytokinesis.
Review Major Concepts
Cell Division
1. In interphase of cell cycle, DNA is replicated (now each of 46 chromosomes has two identical sister chromatids connected to one another)
2. Apoptosis occurs if the DNA is replicated improperly.
3. In Mitosis, sister chromatids are separated from each other and move to opposite ends of the cell.
a. Prophase – nuclear membrane disassembles, DNA coils, spindle apparatus forms
b. Metaphase – Each chromosome (having 2 sisters) lines up on top of another.
c. Anaphase – sisters split apart and move toward opposite ends of the cell
d. Telophase – chromosomes uncoil, spindle disassembles, nuclear membrane forms around two groups of chromosomes.
4. Cytokinesis – The dividing cell is split into two with a cell membrane surrounding each set of chromosomes
1. In interphase of cell cycle, DNA is replicated (now each of 46 chromosomes has two identical sister chromatids connected to one another)
2. Apoptosis occurs if the DNA is replicated improperly.
3. In Mitosis, sister chromatids are separated from each other and move to opposite ends of the cell.
a. Prophase – nuclear membrane disassembles, DNA coils, spindle apparatus forms
b. Metaphase – Each chromosome (having 2 sisters) lines up on top of another.
c. Anaphase – sisters split apart and move toward opposite ends of the cell
d. Telophase – chromosomes uncoil, spindle disassembles, nuclear membrane forms around two groups of chromosomes.
4. Cytokinesis – The dividing cell is split into two with a cell membrane surrounding each set of chromosomes