Biol test 2 notes

Biol test 2 notes - Cell Membrane Cytoskeleton o o Provides structure to the cell Initially cytoplasm(ground substance was thought to be without

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Cell Membrane - Cytoskeleton o Provides structure to the cell o Initially cytoplasm (ground substance) was thought to be without structure Improved techniques showed this to be - Flagella and Cilia o Organelles involved in movement o Bacteria have “flagella” but are constructed differently than in Eukaryotes o Same structural design in flagella and cilia o 9+2 structure- only in Eukaryotes (absent in higher plants (flowering plants)) Basic design feature Different than the flagella of bacteria o Flagella larger and fewer in number than cilia - Sliding filaments o Proteins involved in movement E.g., actin and myosin - Molecular Motors o Proteins o Use ATP - Centriole o In animals (not in higher plants) o Found in Eukaryotes o Similar to the base of a flagellum or cilium o Involved in mitosis and meiosis - The Problem
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o The interior of a cell is different than its environment o How to defend the internal environment but still communicate with the external environment Transport materials across the barrier - An optimal intermediate “Fluidity” o Not too solid o Not too fluid o Preserves membrane function o Do not take “fluidity” too literally o Unsaturated fats increase the fluidity of the membrane - Henrique and Hansen 1900 o Membrane fluidity can acclimate o Membrane fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids - Transport Processes o Active Against concentration gradient Requires supplied energy (ATP) Carrier molecule o Passive Down concentration gradient Does not require supplied energy Diffusion (simple or facilitated) - Diffusion o Movement of molecules down concentration gradient
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o From regions of high concentration to low concentration regions o Physical property of matter o Individual molecules move randomly, but the net effect is non-random - Membrane Permeability o Size and shape of molecules o Solubility in lipids o Net electric charge o Other chemical properties o Water always freely permeable Aquaporins- channel protein which facilitate water diffusion through the membrane - Osmosis o The net movement of water across (through) a semi-permeable membrane o Diffusion of water o From higher (fewer solutes) water potential to lower water potential - Problems confronting organisms o What if the concentration of solutes differs between the intracellular compartment and the environment? o Examples Marine invertebrates (shrimp, crabs) Isotonic with seawater Accumulate free amino acids to match the tonicity of seawater Marine Elasmobranch fishes (sharks, rays) Isotonic with seawater Accumulate up to .5 M urea
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Freshwater bony fish (teleost fish) Hypertonic to freshwater Marine bony fish (teleost fish) Hypotonic to seawater - Hypertonic o Lower water potential o More solutes dissolved o Hypertonic solutions will tend to gain water - Hypotonic o Higher water potential o Fewer solutes dissolved o Hypotonic solutions will tend to lose water
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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Biol test 2 notes - Cell Membrane Cytoskeleton o o Provides structure to the cell Initially cytoplasm(ground substance was thought to be without

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