Lecture 10-02 - Lecture 10-02: Ch. 9...

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Lecture 10-02: Ch. 9 Bioenergetics/Thermodynamics METABOLISM convert nutrient molecules into building blocks assemble building blocks into macromolecules (protein, nucleic acids, lipids, polysaccharides) , then assemble macromolecules into cells Two major activities in metabolism Catabolism-degradative, oxidative, energy yielding Anabolism-synthetic, reductive, energy consuming opposite, but not simply reversal of reactions share some common metabolites, but have different control points to prevent "futile" cycles Stages to catabolism/anabolism nutrient molecules hydrolyzed to building blocks--break down of glycogen (animals)/amylose (plant) to glucose; proteins to amino acids; nucleic acids to nucleotides
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building blocks converted to easily oxidized forms (2 and 3 carbon intermediates)--- acetyl-CoA being the most important, it is the end product of glycolysis and fatty acid degradation Energy is captured by linking ATP synthesis to electron transport pathway new molecules resynthesized using energy derived from ATP cells are constantly breaking down and resynthesizing molecules Degradative mechanisms of cellular polymers (polysaccharides, proteins) into monomeric units (monosaccharides, amino acids) are the source of metabolic energy (ATP). Nucleic acids and nucleotides are not a significant source of metabolic energy. Technically TAGs are not really polymers, fatty acids are linked to glycerol--not a real polymer--but a significant source of energy.
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hydrolysis of sugar polymers (amylose, amylopectin) to monosaccharides by enzymes (amylase) hydrolysis of proteins to amino acids by enzymes (trypsin, chymotrypsin, elastase) hydrolysis of ester bonds of TAGs by lipases to release FAs and glycerol primary fuel stores are from food--glucose, amino acids plentiful after a meal when these are exhausted, first moblize glucose stores--break down glycogen in muscles and liver--during a marathon Phosphorolysis--degradation of glycogen (similar to starch, but with more branching) with inorganic phosphate to give glucose-1-phosphate; may either enter glycolysis directly or be dephosphorylated to glucose (enter bloodstream for transport to other tissues)
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excess glucose is put into storage as glycogen or metabolized to Ac-CoA and used to synthesize fatty acids (all excess carbohydrate ends up as fat. ...... ) glucose is primary fuel for most tissues--heart muscle uses fatty acids as source of Ac- CoA liver is the primary glucose sensing organ--when glucose is needed liver breaks down glycogen stores and sends glucose to blood stream Fat Moblization--when glucose supplies are low (all glycogen expended) adipose tissue mobilizes fat stores and breaks down fatty acids for enery units (acetyl CoA) fatty acids are bound to circulating proteins when released by adipose tissues by lipases fats are only moblized for energy when carbohydrates and amino acids are not sufficient in diet--why must to lots of exercise (running, swimming, biking) to burn off stored fat
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This note was uploaded on 12/31/2010 for the course CH 369 taught by Professor Kbrowning during the Spring '07 term at University of Texas at Austin.

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Lecture 10-02 - Lecture 10-02: Ch. 9...

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