1. Since lactate is a "dead end" product of metabolism in the sense that its sole fate is to be converted into pyruvate, what is the purpose of its formation?
2. The molecule 2, 4 -dinitrophenol (DNP) is an uncoupler of oxidative phosphorylation. For a short period of time, it was prescribed clinically as a pill for weight reduction (against the advice of ssientists). Explain the basis for its ability to cause weight loss.
3. Consider the following reactions, which are two consecutive steps in the cyclic, multistep metabolic pathway referred to as the Kreb's cycle. The first reaction, which is not thermodynamically spontaneous, immediately precedes the second reaction, which occurs spontaneously. The two reactions are catalyzed by two independent enzymes.
L-malate + NAD plus<----> oxaloacetate + NADH + H plus +7(delta G knot --KJ/mol)
Acetyl - CoA + oxaloacetate <----------> citrate +CoA -8( " " " " " )
How can the initial reaction occur in this pathway with such a high positive standard free energy?