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Do Now: We have spent the spent the majority of the year exploring the molecules that are used by and construct cells. We have discussed ways those materials interact in metabolic processes in individual cells and how messages are passed between cells. Think about an individual cell – any cell in your body – what does its life cycle look like from “birth” to “death.” Discuss your ideas with a partner and create a model to show where this cell came from, what it does on a daily basis, and ultimately how it dies (be mindful of time). If the life cycle of a cell was a clock… G1 – Growth & metabolism S – DNA replicated for cell division G2– Additional growth & prep for division Where is all of the information kept that allows this cycle to occur at all? What is the molecule that is stored there? Brainstorm! What DNA’s purpose? What does it “tell” the cell to do? How does DNA relay this information to the cell? What does this look like? Draw a diagram to illustrate your ideas. Can this information sharing ever be disrupted? By what? What do you think the implications would be? Provide a specific example based on your brainstorming ideas. Reviewing the Cell Cycle Which phase are most cells in? What can you conclude about the stage cells spend most of the their life in? Two Periods 1. Growth Interphase Size ↑ Metabolism Chromosomes copied 2. Division Mitosis 2 daughter cells formed Cytokinesis Cytoplasm divides **Size, DNA, nuclear envelope** The Cell Cycle Clock Interphase Longest period 3 phases: 1. G1 – cell grows and develops; chromosomes unclear During G1 the cell receives 1 of 2 signals: 1. Mature – no more division 2. Divide (restriction point, R): prepare for mitosis 2. S – DNA rep, form sister chromatids connected by centromere 3. G2 – chromosomes condense, proteins & organelles made to prep for division Mitosis FOUR stages → 2 identical cells Prophase Longest phase Chromatin coils to chromosomes Nuclear envelope begins to disappear – nucleolus disintegrates Centrioles migrate to opposite ends Spindle fibers appear between centrioles Metaphase Short second phase Spindle fibers attach at centromere Chromosomes line up at equator Each chromatid attached to own spindle fiber – 1 at one pole, 1 at the other Anaphase Separation of sister chromatids Centromeres split, pair separated Chromatids pulled apart as spindle fibers shorten Telophase Chromatids reach opposite ends Start to unwind Spindles break down Nucleolus reappears, nuclear envelope develops – membrane reforms Cytokinesis Division of cells Animal cells – pinch at equator Plant cells – “plate” laid around sister cells, 2 cell walls form Controls at multiple points make sure the process is occurring correctly! Cells out of control! Result in outgrowths - tumors 2 types: BENIGN & MALIGNANT Benign tumors push structures out of the way Malignant tumors are CANCEROUS!! Common Types of Cancer Lung Liver Colon Skin Cervical Ovarian Breast •Influenced by biological and environmental factors • Common treatment •paths Difficult to detect. – surgery and Risks increase with chemo/radiation age; therapy symptoms include abdominal pains & swelling, fatigue • Treatment usually includes surgery & chemotherapy