biol1201 test 2 notes

biol1201 test 2 notes - The Problem o The interior of a...

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The Problem 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 o Sodium Intra cellular 5-15 mM; Outside Extra cellular concentration 145 mM; Potassium Intracellular concentration 140; Extra cellular 5 o Environment on inside and outside of cells is different o Plasma membrane (phospholipid by layer) separates outside and inside of a cell o Figure 7.2, 7.3 Henrique and Hansen 1900-Pigs in underwear o Membrane fluidity can acclimate o Membrane fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids o To make a membrane more fluid which class of fats would you increase saturated or unsaturated? Increase unsaturated fats increase fluidity of the membrane Transport Processes o Active - against concentration gradient, Requires supplied energy (ATP), Carrier molecule Figure 7.16 o Passive- down concentration gradient, does not require additional energy, diffusion (simple or facilitated) Figure 7.15 diffusion- Movement of molecules down concentration gradient; From regions of high concentration to low concentrations. No carrier molecules involved o Osmosis- diffusion of water; from higher (fewer solutes) water potential to lower water potential Figure 7.12 Problems confronting organisms o What if the concentration of solutes differs between the intracellular compartment and the environment 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 Isotonic o Equivalent water potential o Equivalent number of solutes dissolved o No net movement of water Figure 7.13 Maine Invertebrates o Isotonic with seawater
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o Accumulate free amino acids to match the tonicity of seawater o Isotonic marine invertebrates tend to neither gain nor lose water Marine elasmobranch fishes o Sharks and rays; isotonic with sea water o Accumulate up to .5 M urea to ensure they have the same amount of dissolved solutes as that of sea water Freshwater bony fish (teleost fish) o Hypertonic to freshwater; marine bony fish hypotonic to seawater o Freshwater teleost fish tend to: gain water o Marine teleost fish tend to: lose water How do cells regulate metabolism? o How do cells organize and control the chemical reactions that support life? Metabolic Transformations: o Chemical reactions o Small steps o Controlled processes (tightly) o Each step is controlled by a protein catalyst (enzyme) Biological Chemical Reactions o Regulated by protein catalysts (enzymes) o Synthesis of energy carrier molecules to store energy, transport it from place to place and regulate its flow o Couple reactions together so that unfavorable reactions can occur at the expense of reactions that release energy Enzymes o Protein catalysts o Not used up (recycled) o Specific reactions require specific enzymes o Enzymes lower activation energy barrier o
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biol1201 test 2 notes - The Problem o The interior of a...

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