Biology Chapter 04-3

Biology Chapter 04-3 - initially called resting phase of...

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Chapter 4 Section 3 - The Cell Cycle By the time it takes you to read this sentence, your body will have made millions of  new cells! Making new cells allows you to grow and replace cells that have died. The environment in your stomach is so acidic that the lining in your stomach must  be replaced every few days. Your cells also pass through different stages in their life cycle. Cell cycle - the life cycle of a cell. The cell cycle begins when the cell is formed and ends when the cell divides to form new cells. Before a cell can divide, it must make a copy of its DNA. DNA is organized into structures called chromosomes . Why is it important to copy chromosomes before dividing? Copying chromosomes ensures that each new cell will be an exact copy of its parent cell. Life Cycle of Cell 2 divisions: interphase and cell division. Interphase period of time from cell formation to cell division.
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Unformatted text preview: initially called resting phase of cell cycle. better name is metabolic phase. 1 Cell Division involves 2 events: mitosis and cytokinesis Mitosis -nuclear division diploid – division of 46 chromosomes both parent and daughter cell are genetically identical Made of 4 phases: prophase, metaphase, anaphase, telophase 4 Stages of Mitosis Prophase – chromatin forms chromosomes Metaphase – chromosomes align on equator of spindle Anaphase – chromosomes move toward opposite poles Telophase – nuclear membrane and nucleoli reappear Cytokinesis division of cytoplasm; begins in late anaphase. http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi? it=swf::535::535::/sites/dl/free/0072437316/120073/bio14.swf::Mitosi s%20and%20Cytokinesis Meiosis Occurs only in sex organs (gonads) Sperm and egg each contribute 23 chromosomes (haploid) Zygote produced is different than parents. 2...
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Biology Chapter 04-3 - initially called resting phase of...

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