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| The Life Span of a cell includes? | Mitosis-cell division; Interphase-most of the time the cell is in this cycle |
| What is interphase ? | The period that covers all the time the cell is not undergoing mitosis |
| What is Mitosis? | The orderly events that involve the division of the nucleus |
| What are the diff. phases of the cell cycle? | G0, G1, G2, S |
| G1 Phase (pre) | Variable in length (1 yr, hrs, days); Protein Synthesis; Regains normal size-Cell Growth; Checkpt. prior to entry to S phase (is enviro. favorable for division? is DNA intact?) |
| S Phase | DNA is replicated; 6-8 hrs. in length; Semiconservative Replication (old & new strands) |
| G2 Phase (post) | Completes preparation for cell division; 3-6 hours in length; Synthesis of tubulin for microtubules; Checkpt. for repair of DNA (has DNA totally replicated?) |
| M Phase | Mitosis; 1-2 hours in length |
| G0 | Entered from G1; Cell is not dividing but still active b/c there's sufficient supply of that type of cell; Cardiac muscle and neurons permanently in G1 |
| The cell cycle is regulated by what? | External and Internal factors |
| External Regulation | Specific receptors on the cell surface send cytoplasmic signals to cellular components to divide |
| Internal Regulation | Regulated by Cyclins & Maturation promoting factor (MPF) |
| What are cyclins? | Proteins that bind to specific kinases to regulate events of interphase (cell cycle) |
| What is MPF? | cyclin M + kinase; Rapid increase of the protein triggers cell entry into Mitosis |
| Mitosis is made up of what two main stages? | Karyonkinesis-nuclear division and Cytokinesis-division of the cytoplasm |
| Karyokinesis has how many stages? | 4-Prophase, Metaphase, Anaphase, Telophase |
| Prophase | Chromosomes appear; Nuclear envelope breaks down; Centrosomes separate to opp. poles |
| Metaphase | Chromosomes migrate to Equatorial Plane; Chromosomes separate into sister chromatids |
| Anaphase | Chromatids move to opp. poles; Cytokinesis begins |
| Telophase | Chromosomes disperse; Nuclear envelope regenerated; cytokinesis completed |
| What is cytokinesis? | The division of the cytoplasm during Mitosis |
| What occurs in the cell during cytokinesis? | Band of actin filaments form at equatorial plane; constriction of band separates cytoplasm; begins at anaphase and end in telophase |
| What is Apoptosis? | Programmed cell death |
| Apoptosis can occur during what two stages of life? | Embryonic development and Adult Life |
| Apoptosis in Embryo Develop. | Normal reorganization of tissues; Ex. developing hand & foot once those are completed not all cells used to form are needed |
| Apoptosis in Adult Life | Occurs to balance cell divisions; removes cells that are damaged or ineffective; Nucleus condenses and breaks up; Does NOT initiate an inflammatory response |
