HW #12 - AP Biology Period 4 Liem Nguyen #22 10/24/09...

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AP Biology Period – 4 Liem Nguyen #22 10/24/09 Homework #12 (091030): Chapter 12 (due Friday 091030 ) Total points: 20 for Attempt on all questions ONE Concept Map: 10 points Objectives The Key Roles of Cell Division 1. Explain how cell division functions in reproduction, growth, and repair. -cell division: reproduction of cells -continuity of life based on cell division -produce progeny (multicellular organisms) -allows sexually reproducing organisms to develop -repairs by replacing cells that die The continuity of life is based on reproduction of cells, or cell division. Cell division can produce progeny from some multicellular organisms. Cell division enables sexually reproducing organisms to develop from a single cell. After an organism has fully grown, cell division continues to function repair, replacing cells that die. 2. Describe the structural organization of a prokaryotic and a eukaryotic genome. -genome: genetic info. (DNA) -prokaryotic: single long DNA molecule -eukaryotic: enormous length of large # of DNA molecules Genome is a cell’s endowment of DNA, its genetic information. Prokaryotic genome is a single long DNA molecule. Eukaryotic genome is enormous in length and has a large number of DNA molecules. 3. Describe the major events of cell division that enable the genome of one cell to be passed on to two daughter cells. -mitosis: division of nucleus, followed by cytokinesis -cytokinesis: division of cytoplasm -meiosis: results in cells with half the chromosome # of original cell Mitosis is the division of the nucleus, and is followed by cytokinesis, the division of the cytoplasm. Then there is meiosis, a variation of cell division, which yield nonidentical daughter cells that have only one set of chromosomes. 4. Describe how chromosome number changes throughout the human life cycle. -offspring inherit 46, 23 from each parent -meiosis reduces chromosome # from 46 to 23 in each generation of humans -fertilization fuses gametes together, return # to 46
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In each generation of humans throughout the life cycle, meiosis reduces the chromosome number from 46 (2 sets) to 23 (1 set). Fertilization then fuses the gametes together, returning the chromosome number count to 46. The Mitotic Cell Cycle 5. List the phases of the cell cycle and describe the sequence of events that occurs during each phase. -mitotic (M) phase: mitosis and cytokinesis (shortest) -interphase: alternates with mitotic cell division (longest), has 3 subphases 1. G 1 phase “first gap” 2. S phase “synthesis” 3. G 2 phase “second gap” -cell grows by producing proteins and cytoplasmic organelles during interphase The mitotic (M) phase includes mitosis and cytokinesis. Mitotic cell division alternates with a larger stage, interphase. Interphase is divided into G 1 phase, S phase, and the G 2 phase. During these 3 subdivided stages, cell grows by producing proteins and cytoplasmic organelles.
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HW #12 - AP Biology Period 4 Liem Nguyen #22 10/24/09...

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