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Metabolism Metabolism = Energy released during catabolic metabolism goes to: How is metabolism regulated?. Important in Metabolic Pathways Oxidation/Reduction reactions Substrate-level phosphorylations Oxidative phosphorylation Decarboxylations Coupled reactions. Oxidation/Reduction
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Metabolism • Metabolism = • Energy released during catabolic metabolism goes to: • How is metabolism regulated?
Important in Metabolic Pathways • Oxidation/Reduction reactions • Substrate-level phosphorylations • Oxidative phosphorylation • Decarboxylations • Coupled reactions
Oxidation/Reduction Glyceraldehyde 3-phosphate 3-phosphoglycerate NAD+ NADH + H+ Pi Figure 4-5
Glycolysis (glyco = sugar; lysis = to break down) Where do reactions of glycolysis occur in the cell? Where does the glucose (or other sugar) come from? Do these reactions need oxygen to generate energy? What is the end-product of glycolysis? Figure 4-13
Test Your Knowledge: • Put a next to any oxidation/reduction reaction • Put a next to any substrate-level phosphorylation reaction • Which reactions do you think have a DG that is negative (exergonic)? Label them with a • Which reactions do you think have a DG that is positive (endergonic)? Label them with a • How many ATP are made by the breakdown of one glucose to two pyruvate molecules? • How many ATP are utilized to break down one glucose molecule into two pyruvate molecules? • What do you think happens to the two pyruvate molecules generated? • What else is made in glycolysis that might eventually produce energy? Figure 4-14
From glycolysis From glycolysis Anaerobic vs. Aerobic Metabolism of Pyruvate Figure 4-15
pyruvate Figure 4-16
pyruvate CO2 NAD+ NADH • What types of reactions do you see occurring frequently in this cycle? • Is oxygen required in this cycle? • How many ATP (or other high energy nucleotides) are generated from one pyruvate molecule? Figure 4-16
High Energy Electrons carried by NADH and FADH2 Go to the Electron Transport Chain TEST YOUR KNOWLEDGE Where is the electron transport chain located? What kind of biomolecules make up the electron transport chain? What are the important functions of these biomolecules? Is oxygen required for the electron transport chain to function? If so, what is its role? The electron transport chain is where oxidative phosphorylation occurs. Where does the oxidation occur? How about the phosphorylation?
High-energy electrons are carried by NADH +H+ or FADH2 Electron transport proteins: two functions ATP synthase O2 and H2O Figure 4-17
Test Your Knowledge: • Follow one glucose molecule through glycolysis, the Krebs cycle, and the electron transport chain. Calculate: • How many NADH + H+ molecules are generated • How many FADH2 molecules are generated • How many ATPs are produced by substrate-level phosphorylation • How many ATPs are produced by oxidative phosphorylation • How many CO2 molecules are produced • How many O2 molecules are consumed (used) • How many H2O molecules are produced
What about sugars besides glucose? ADP ATP Fructose 6-phosphate glycolysis hexokinase • galactose from milk sugar (lactose) to glucose-6-phosphate (1 ATP used) • Mannose from polysaccharrides and glycoproteins to fructose-6-phosphate to glucose-6 phosphate (1 ATP used)
Carbon skeleton determines the fate of the amino acid glucogenic vs. ketogenic Alanine pyruvate
One NADH and one FADH2 made for each 2-carbons cut from the chain in b oxidation Problem: If lipase cuts off a 16-carbon fatty acid from a triglyceride, and it is metabolized completely, how many ATPs will be produced? Figure 4-20
Regulation of Metabolism • Major role is to regulate blood glucose • Regulation in response to ATP/ADP ratio • Regulation to adjust NAD+/NADH ratio • Regulates to reduce loss of energy • All regulation occurs through changes in enzyme activity
Which enzymes in glycolysis do you think might be regulated? For what reason? List at least 3 and the reason why you think they would need to be regulated.