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Unformatted text preview: Chapter 7 • All the energy initially comes from the sun- the ultimate source of energy. In body, heat energy maintains a constant body temp and electrical energy sends nerve impulses. During metabolism, the body releases energy, water and carbon dioxide. • Metabolism includes all the ways the body obtains and uses energy from food. The liver cells are most important for metabolic activity. The building up of body compounds is known as anabolism. Glycolysis: glucose-to-pyruvate A little ATP is used to start glycolysis galactose and fructose enter glycolysis at different → places, but all continue on the same pathway in a series of reactions, the 6-carbon glucose → is converted to other 6-carbon compounds, which eventually split into 2 interchangeable 3- carbon compounds a little ATP is produced, and coenzymes carry the hydrogen and their → electrons to the electron transport chain these 3-carbon compounds are converted to → pyruvate. Glycolysis of one molecule of glucose produces 2 molecules of pyruvate Glycerol and Fatty acids • Fatty acids are broken apart into 2-carbon fragments that combine with CoA to make acetyl CoA. o Fatty acid is first activated by coenzyme A as each C-C bond is cleaved, → hydrogen and their electrons are released, and coenzymes pick them up → another CoA joins the chain, and the bond at the 2 nd carbon weaken. Acetyl CoA splits off, leaving a fatty acid that is 2 carbons shorter → shorter fatty acid enters the pathway and the cycle repeats, releasing more hydrogen w/ their electrons and more acetyl CoA. The molecules of acetyl CoA enter the TCA cycle, and the coenzymes carry the hydrogen and their electrons to the electron transport chain. ( 2-C fatty acid CoA = acetyl CoA) • Significance of fatty acids is that red blood cells and brain and nervous system depend primarily on glucose as fuel. • Body can convert small glycerol port ion of t riglyceride to either pyruvate or acetyl CoA. Fat ty acids of a t riglyceride cannot make glucose, but can provide abundant acetyl CoA which enters the TCA cycle to release energy or combine w/ other molecules of acetyl CoA to make body fat....
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This note was uploaded on 01/30/2011 for the course GCH 295 taught by Professor Unknown during the Fall '07 term at George Mason.
- Fall '07