10-19-09_TCA

10-19-09_TCA - How do we make the energy for all this...

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How do we make the energy for all this transport and other processes? C ATP
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Mitochondria produce much of the chemical energy in eukaryotes Consists of outer and inner membranes and intermembrane space Inner membrane distinct but continuous with cristae, on which ATP synthase molecules are concentrated Intermembrane space has some signaling proteins, especially to trigger apoptosis (programmed cell death) Inner membrane encloses matrix, where reactions take place. Contains ribosomes and mitochondrial DNA Mitochondrial DNA distinct from chromosomal DNA, 13 proteins, 2 rRNAs, 22 tRNAs encoded. Passes through mother only and used to study human migration/evolution
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Mitochondrial function is significantly correlated with lifespan and mental acuity Navarro and Boveris 2007
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Analysis of mitochondrial and genomic DNA supports African origins of humans and can help to track historical migrations Stix 2008, Scientific American
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Locations of different energy producing processes in the cell
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Pathways from pyruvate 1) Lose a CO 2 , regenerate NAD+, end with ethanol 2) Regenerate NAD+, reduce pyruvate to lactate 3) If NAD+ not regenerated, glycolysis will shut down 4) Both of these reactions are anaerobic, meaning no O 2 required, and considered fermentation 5) Create another NADH, form acetyl CoA, enter TCA cycle for aerobic respiration using O 2
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Overall reaction of TCA Cycle
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The products of glycolysis begin the TCA cycle Pyruvate transported across inner mitochondrial membrane to matrix HS-CoA is a coenzyme, or a non-protein enzyme component. Variant of pantothenic acid (Vitamin B5). Pyrvuate+HS-CoA+NAD + → acetyl CoA + CO 2 + NADH + H + Pyruvate dehydrogenase catalyzes this NAD+ is shared with glycoysis NADH will be used later Now enters the TCA cycle All enzymes for TCA cycle in matrix except for succinate dehydrogenase in inner membrane
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Beginning of TCA cycle In this diagram 2 and 3 refer to positions of carbon from original pyruvate w,x,y,z refer to carbons from oxaloacetate so that they can be tracked Formation of a 6 carbon molecule begins TCA cycle Acetyl CoA + oxaloacetate + H 2 0 → citrate + HS-CoA (condensation rxn) catalyzed by citrase synthase, energetically very favorable Reshaped to isocitrate by aconitase (dehydration then hydration)
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Isocitrate + NAD+ → α-ketoglutarate + CO
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10-19-09_TCA - How do we make the energy for all this...

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