Kreb’s Cycle Pyruvic acid (from glycolysis) goes into the mitochondria CO 2 + H + are split off and leaves a 2 carbon (acetyl) Group http://www.science.smith.edu/departments/Biology/Bio231/krebs.html (step 1) http://www.science.smith.edu/departments/Biology/Bio231/krebs.html Acetyl group combines w/ CoA acetyl CoA
Coenzyme Organic compound made by cells that must combine with an enzyme in order to work. Coenzyme may be a hydrogen “carrier”
Coenzyme A Coenzyme that is NOT a hydrogen carrier. Coenzyme A carries a 2-carbon (acetyl) group
ADP Is also a coenzyme – carries phosphate groups
First part of Kreb’s cycle CoA carries acetyl groups into the Kreb’s cycle to transfer them to oxaloacetic acid to form CITRIC ACID (name of cycle) http://www.science.smith.edu/departments/Biology/Bio231/krebs.htmlhttp://www.science.smith.edu/departments/Biology/Bio231/krebs.html (step 2)
Kreb’s cycle is important in the metabolism of: Carbohydrates Proteins Lipids
In one “turn” of the Kreb’s cycle….. 2 molecules CO 2 4 molecules H 2 (3 NADH + 1FADH) 1 molecule acetyl CoA 1 molecule ATP
Summary to end of Kreb’s Cycle InOut 1 pyruvic acid1 CO 2 (as waste) 1 NAD1 NADH CoAAcetyl CoA 1 acetyl CoA2 CO 2 (as waste) 3 NAD3 NADH 1 FAD1 FADH 2 1 ADP1 ATP
What happens to the CO 2 produced in the Kreb’s Cycle? Diffuses from mitochondria cytoplasm (cytosol) bloodstream exhaled (whew!)
Electron Transport Chain The pairs of hydrogen ions (-2H) from the Kreb’s Cycle enter the electron transport chain. There are a series of HYDROGEN ACCEPTORS (NAD, FAD & cytochromes) that, as they pass the hydrogen ions along, ATP is being produced.
What ultimately happens to pairs of H? Oxygen is final acceptor of H produces H 2 O! From 4 pairs of H 36-38 ATPs produced in the electron transport chain!
Glucose ATP count? Phosphorylation & glycolysis: 8 ATP Kreb’s cycle & electron transport: 30 ATP Total = 38 ATPs
Electron Transport Chain (Animation) http://www.science.smith.edu/departments/Biology/Bio231/etc.html
Fat metabolism 1 unit of FAT 3 fatty acids 1 glycerol 18 C each chain glycolysis Kreb’s cycle & electron transport 38 ATP Each 18 C 6 pyruvic acid So total of 18 pyruvic acids 18 pyruvic acids 684 ATP So, 684 + 38 = 722 ATPs!
What about protein? Single amino acids are used to build muscle, bones, connective tissue, and cytoplasm and cell membrane of cells. Not typically catabolized (broken down) for energy – only during starvation. 22 amino acids – 8 are “essential”
Chemistry of Digestion writing prompt: The carbohydrates, proteins and lipids have now been broken down into single sugars, amino acids or fatty acids and glycerol. They are now in the liver. Describe, in detail, the process by which glucose creates ATP and then how the other substances become ATP as well. Be sure to include structures to help your explanation.
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