phosphorylation

1. The first step in the payoff phase of glycolysis is catalyzed by the enzyme glyceraldehyde 3-phosphate dehydrogenase, an enzyme that contains a nucleophilic cysteine playing a central role in the reaction. A) In the direction of gluconeogenesis, what reaction does this enzyme catalyze? AG° = -6.3 kcal/mol for this reaction in the direction of gluconeogenesis. Based on what you know about the substrates involved, provide two chemical reasons as to why the AGO of this reaction is negative.

1. Cyanide, oligomycin, and 2,4-dinitrophenol are all inhibitors of oxidative phosphorylation in mitochon- dria. Provide an explanation to the following conditions regarding these potent inhibitors. (a) Explain why adding cyanide to an active in vitro suspension of mitochondria blocks ATP synthesis. What happens to the rate of ATP synthesis when 2,4-dinitrophenol is added to this mitochon- drial suspension after it was treated with cyanide? (b) Explain why the rate of oxygen consumption decreases in an in vitro suspension of mito- chondria when oligomycin is added. What happens to the rate of oxygen consumption in this oligomycin- inhibited system after adding 2,4-dinitrophenol? Explain.

a. A peptide fragment MVEY is degraded to individual amino acids and ultimately their four respective carbon skeletons. b. How much NADH, FADH2, and (A or G)TP will be produced from the oxidation of these carbon skeletons as they complete the TCA cycle? c.How much total ATP will be generated after the resulting electron carriers complete the electron transport chain?