EXAM 2 BIO

EXAM 2 BIO - Passive transport: Movement down the...

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Unformatted text preview: Passive transport: Movement down the concentration gradient Employs a carrier molecule Active transport Requires energy Employs a carrier molecule Osmosis Diffusion of water From higher (fewer solutes) water potential to lower water potential Problems confronting organisms What if concentration of solutes differ between the intracellular compartment and the environment? Hypertonic Lower water potential More solutes dissolved Hypertonic solutions will tend to gain water Hypotonic Higher water potential Fewer solutes dissolved Hypotonic solutions will tend to lose water Isotonic Equivalent water potential Equivalent number of solutes dissolved No net movement of water (although water is still moving) *Fig 7.13 Dehydrated Person When solute concentrations are equal on both sides of the diffusion barrier the molecules no longer move: False Problems confronting organisms What if concentration of solutes differs Marine invertibrates Isotonic with seawater Accumulate free amino acids to match the tonicity if seawater Marine elasmobranch fishes (Sharks and Rays) Sharks and rays Isotonic with seawater Accumulate up to 0.5 M urea in their tissue Freshwater bony fish (teleost fish) Hypertonic to fresh water Marine bony fish (teleost fish) Hypotonic to seawater Isotonic marine invertebrates tend to: Neither gain nor lose water Freshwater teleost fish tend to: Gain water Marine teleost fish tend to: Lose water Endocytosis Cell engulfs object, becomes membranes bound vesicle Phagocytosis large object Pinocytosis small object Receptor-mediated endocytosis Fig. 7.20 Excocytosis Membrane bound vesicle fuse with cell membrane and expel contents Fig 7.14 Aquaporins Exocytosis Endocytosis o o o What kind of molecules would pass through a membrane, i.e., a phospholipid bilayer: Small and non-polar molecules Which way will water flow?: To the right(the higher sugar concentration) A marine teleost fish is_______ to sea water: Hypotonic A marine teleost fish will tend to ________ water Lose How do cells regulate metabolism? Metabolism=Biological chemical reactions True How do cells organize and control the chemical reactions that support life? Metabolic transformations Chemical reactions Small steps Controlled processes Each step controlled by a protein catalyst o Enzyme Biological Chemical Reactions Regulated by protein catalyst- enzymes Synthesis of energy carrier molecules to store energy, transport it from place to place, and regulate its flow Couple reactions together so that unfavorable reactions can occur at the expense of reactions that release energy Enzymes Protein catalyst Not used up Specific reactions require specific enzymes Enzymes lower activation energy barrier Enzymes speed up reaction 10 8-10 20 times faster Do not reverse an energetically unfavorable reaction...
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This note was uploaded on 09/08/2011 for the course BIO 1208 taught by Professor Wischusen during the Spring '11 term at LSU.

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EXAM 2 BIO - Passive transport: Movement down the...

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