Cells-2 - Cells TheCellTheory...

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Cells The Cell Theory Robert Hooke (1635-1703 ) first described cells in 1665. Modern cell theory includes four principles: All living organisms are composed of cells. Nothing smaller than a cell is considered to be alive. Life evolved only once, and all living organisms have descended from the earliest cells. Cells arise only from preexisting cells. Why Aren't Cells Larger? Cell size ( Fig 5.3 ) surface area-to-volume relationships ( Fig 5.2 ) cytoplasm . The Plasma Membrane polar ends of phospholipids nonpolar fatty acid chains ( Fig. 5.4 ) bilayer of phospholipids ( Fig.5.5 ). Proteins within the membrane transmembrane proteins cell surface proteins . ( Fig. 5.6 ) Membrane defects. EX: Cystic fibrosis Prokaryotic Cells (before nucleus) = "bacteria" ( Fig 5.9 and Fig. 5.8 ) Prokaryotic cells evolved 2 billion years before eukaryotic cells. Have a rigid cell wall around their plasma membranes , and
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ribosomes , but no internal membrane-bounded organelles. Eukaryotic Cells (true nucleus) = cells of animals ( Fig. 5.10 ), plants ( Fig.5.11 ). **NEW NOTES FROM 9/11** **NEED TO FILL IN ABOVE** Cell Organelles Eukaryotic cells are thought to have evolved as a result of two processes: infolding of the membrane system ( Fig. 20.1 ) and endosymbiosis ( Fig 5.18 ) of several types of bacterial cells ( Fig. 20.2 ). A more detailed image here and here . And a movie ! Mitochondrial DNA is derived from the mother. All of my siblings will
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This note was uploaded on 11/10/2008 for the course BIO 301L taught by Professor Wandelt during the Spring '07 term at University of Texas at Austin.

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Cells-2 - Cells TheCellTheory...

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