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Cell Cycle Cell Cycle – Overview A. Interphase: first, and longest stage of the cell cycle, during which the cell grows, replicates its DNA, and prepares to divide. The phases of interphase are shown below. Cell Cycle – Overview 1. G0 Phase 2. G1 Phase 3. S Phase 4. G2 Phase Cell Cycle – Overview B. MitoJc Phase: second stage of the cell cycle, during which the nucleus is divided. The phases of mitosis are shown below. Cell Cycle – Overview 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Cell Cycle – Overview C. Cytokinesis: the final stage of the cell cycle, during which the cytoplasm divides to form two idenJcal daughter cells. Cell Cycle – Specifics A. Interphase 1. G0 Phase: temporary resJng period or permanent phase of a cell when the cell stops dividing. Not all cells do this. Cell Cycle – Specifics 2. G1 Phase: the cell grows in size, produces RNA, and synthesizes proteins. 3. S Phase: DNA synthesis occurs. 4. G2 Phase: the cell grows in size, produces RNA, and synthesizes proteins. **Organelles and molecules required for cell division are produced. Cell Cycle – Specifics B. MitoJc Phase 1. Prophase: nuclear envelope breaks down and DNA condenses into chromosome form. Tiny structures called centrioles begin to move toward the poles of the cell. Cell Cycle – Specifics 2. Metaphase: chromosomes line up in the middle of the cell. The centrioles produce spindle fibers, which aRach to the chromosomes’ centromere. Cell Cycle – Specifics 3. Anaphase: chromosomes are pulled apart as the spindle fibers shorten. The sister chromaJds are separated as they move towards opposite poles of the cell. Cell Cycle – Specifics 4. Telophase: sister chromaJds arrive at the poles of the cell. The spindle fibers begin to disappear and the nuclear envelope reforms.. Cell Cycle – Specifics • Cytokinesis: cytoplasm is divided and two new, idenJcal daughter cells are formed. The chromosomes return to the chromaJn state. Extra Information • Remember – mitosis is an example of asexual reproducJon as it creates exact copies from one parent cell. • Cells have a sweet spot/perfect size. When a cell becomes too large, it will divide or enter G0 and stop growing. • Chromosomes make is possible to separate DNA precisely during cell division. Extra Information – Purpose of mitosis is to replace worn-‐out cells, enable mulJcellular organisms to grow, keep total cell number of a mature organism relaJvely constant. – Enzymes begin and drive the cell cycle. – Cells that lose control (uncontrolled dividing of cells) leads to cancer. – If a cell realizes it has been made incorrectly, it will self destrucJon itself to avoid further harm to the organism. Back to Notes • Complete the Cell Cycle IllustraJon page of your notes by using the textbook. • Complete the Cell Cycle QuesJon page of your notes using your understanding of the cell cycle.