1a. Interphase (G1 Phase)
The G1 Phase, or Gap 1 Phase is the first phase of the cell cycle that takes place in eukaryotic cell division. During G1, cells grow and synthesize proteins needed for mitosis. These proteins also activate the cell's metabolism and break down the carbohydrates and lipids to transform this food into energy. In the G1, the chromosomes inside the cell have not replicated, so each chromosomes only contain one DNA molecule. "In interphase, the cell gets itself ready for mitosis or meiosis." 2. Prophase
Prophase is the 1st step in mitosis. Mitosis starts to begin (cell begins to divide). In early prophase, the cell starts to break down some structures and build others up, setting the stage for division of the chromosomes.
5. Telophase
Telophase is the 4th step of the mitosis. In telophase, the cell is nearly done dividing, and it starts to re-establish its normal structures as cytokinesis (division of the cell contents) takes place.
"Once anaphase is complete, the cell moves into telophase ." |
1b. Interphase (S Phase)
The S phase follows G1 phase; its major function involves replicating the cell's DNA. The "S" name stands for synthesis. By using enzymes, the cell copies the DNA molecules of each chromosomes. After S phase completes, chromosomes have two chromatids, meaning each chromosome has two molecules of DNA. 3. Metaphase
Metaphase is the 2nd step in mitosis. In metaphase, the spindle has captured all the chromosomes and lined them up at the middle of the cell, ready to divide.
"Metaphase ends with the destruction of B cyclin." 6. Cytokinesis
Cytokinesis occurs after mitosis. Cytokinesis is the process in which the cell actually divides into two. With the two nuclei already at opposite poles of the cell, the cell cytoplasm separates, and the cell pinches in the middle, ultimately leading to cleavage.
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1.C Interphase (G2 Phase)
After the S phase, the cell enters G2, or "Gap 2", and it involves another period of growth; During the gap between the DNA synthesis and mitosis, the cell will continue to grow, produce more proteins and organelles like mitochondria grow and divide. The cell also resumes normal functions like transforming food into fuel; as cell stocks up on this energy for its use in mitosis. At the end of this phase is another control checkpoint to determine if the cell can now proceed to enter mitosis and divide as G2 is the final step before a cell enters the first stage of mitosis. 4. Anaphase
Anapahse is the 3rd step in mitosis. In anaphase, the sister chromatids separate from each other and are pulled towards opposite ends of the cell.
"The daughter nuclei may have arrived at the anaphase stage, and have even gone the length of forming a nuclear membrane, without an equatorial depression having shown itself in the cell-body." |
Chromosome
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Chromatid
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Centriole
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