| Term | Definition |
|---|
| Interphase and M phase | The two parts or halves of the cell cycle. |
| Interphase | period of the cycle between cell divisions, including G1 phase, S phase and G2 phase |
| M phase | period of time when mitosis and cell division occur |
| G1 phase | Phase including growing, synthesizing new proteins and organelles, and doing their jobs. It is the longest phase of the cell cycle. |
| S phase | Phase where chromosomes (DNA) are replicated and key preoteins associated with replication are made (centromeres) |
| G2 phase | Shortest of the three phases, where organelles and molecules for cell division are produced (centrioles). It is the check up phase before mitosis. |
| chromatin | A complex of DNA and proteins in the cell nucleus that condenses to form chromosomes during cell division. |
| chromosomes | Condensed Chromatin (changes before mitosis begins) |
| False (humans - 46, fruit fly cells - 8, king crab cells - 208) | All organisms have the same number of chromosomes. (True or False?) |
| sister chromatids | Two identical copies of a chromosome made during the cell cycle (before cell division takes place) |
| Centromere | area where the chromatids of a chromosome are attached |
| Prophase, Metaphase, Anaphase, Telophase (PMAT) | The order of Mitosis |
| Prophase | 1st part of mistosis; the chromatin condenses into chromosomes, the nucleoli and nuclear envelope breaks down, the spindle fibers form a bridge across the cell, the centrioles migrate to opposite poles of the cell |
| Metaphase | Chromosomes lined up at equator of cell, spindle fibers from each centriole are attached to the centromeres of the chromosomes, the nuclear membrane has disappeared |
| Anaphase | The centromeres split, and the sister chromatids separate as each is pulled to an opposite pole. |
| Telophase | Last part of mitosis; chromosomes become longer, thinner & less distinct, new nuclear membranes form, nucleolus reappears, cell division is nearly complete. Furrowing occurs. |
| Cytokinesis | Cytoplasmic division and other changes exclusive of nuclear division that are a part of mitosis or meiosis. In plants, a cell plate forms. |
| Internal regulators | proteins that respond to events inside the cell, work in the G2 phase |
| Cyclins | (internal regulator) one of a family of closely related proteins that regulate the cell cycle in eukaryotic cells |
| Cyclins | Protein that periodically rises and falls in concentration in step with the eukaryotic cell cycle. They activate crucial protein kinases (called cyclin-dependent protein kinases, or CDK) and thereby help control the progression from one stage of the cell cycle to the next. Cascade of events!! |
| External Regulators | Proteins that respond to events outside the cell. They direct cells to speed up or slow down the cell cycle. |
| Growth factors | Among the most important external regulators, tells cells to speed up division |
| True | Molecules found on surfaces of neighboring cells often cause cells to slow down or stop their cell cycles (True of False?) |
| p53 gene | Over 50% of cancer cells have a defect in the: |
| True | The common thread in all cancers is that control over the cell cycle has broken down. (True or False? |
| p53 antioncogene | A tumor suppressor gene found mutated in about half of human cancers. It encodes a gene regulatory protein that is activated by damaged DNA and is involved in blocking further progression of the cell cycle. |
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