Organization of Cell Chapter 4

Organization of Cell Chapter 4 - September 3, 2009 Chapter...

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September 3, 2009 Chapter 4 – Organization of the Cell I) Cell Theory a. Smallest unit to carry out activities autonomously i. Maintenance, growth, division ii. Information contained in DNA codes (nucleus) b. All cells come from other cells c. Common Ancestry II) Homeostasis a. Organelles help maintain homeostasis b. Homeostasis: appropriate internal environment which must be retained to allow biochemical function during constant changes in environment i. Organization and size is CRITICAL to maintaining homeostasis III)Structures a. Plasma Membrane i. Separates cell from ext. environ ii. Maintains internal conditions for function iii. Allows cell to change materials with outer environment iv. Can increase energy level with signals v. Encloses internal structures (organelles) 1. Genetic material : DNA, RNA 2. Metabolic integrity (energy conversion) 3. Manufacture (function and reproduction) b. Prokaryotic and Eukaryotic i. Prokaryotic 1. Cells lack internal membrane organization a. Include a cell wall that surrounds the plasma membrane (extra external layer) – advantageous and disadvantage
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b. Lack of organization can be advantageous for reproduction 2. Eukaryotic a. Divided into compartments by internal membranes b. Membranes provide separate, small areas for specialized activities c. Most cells are microscopic ii. Meter 1. (mm) millimeter – 1/1000 m = !0^-3 m 2. (um) micrometer – 1/1000,000 m = !0^-6 m 3. (nm) nanometer – 1/1000,000,000 = 10^-9 m c. Cells are small i. Short distances between molecules traveling to their destinations – increases speed of reaction ii. Size must be limited or molecules required by the cell cannot be transported fast enough to sustain need 1. Food in, waste out 2. Pumps and gates for ion and molecular transportation iii. Surface to Volume Ratio iv. SVR 1. Ratio of plasma membrane (surface area) to cells volume a. Regulates passage of materials into and out b. Increases according to cell shape i. Example: mircovilli 2. Surface must be big or increased enough to adequately exchange materials with the environment v. Size and shape are related to function IV)Microscopes a. Anton Van Leeuwenhock; Royal Society of London i. First to report cells in animals
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b. Techniques not developed for 100 years i. 19 th Century and microscopes 1. light microscopes 2. Electron microscopes a. Superior resolving power c. Parts of the Microscope i. Ocular Lens ii. Objective lens iii. Specimen iv. Condenser Lens v. Light sources d. Magnification and Resolution i. Magnification 1. The ratio of the image size to actual size ii. Resolution 1. Minimum distance between 2 points where both can be seen separately without blur 2. Distinguishes fine detail 3. Decrease in wavelength = decrease in V) Light Microscopy a. Light Microscope i. Most staining kills cells ii. Viewing living cells requires special optics 1. Bright field – transmits light through a cell – no detail 2. Dark field – scatters light so that the cell is bright against a
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Organization of Cell Chapter 4 - September 3, 2009 Chapter...

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