StepChem/Biol 472 W04 First Exam January 28, 2004 Name___________1. (6 points) Given these molecular components—glycerol, fatty acid, phosphate, long-chain alcohol and carbohydrate, answer the following:a. Which 2 are present in both fats and phosphotidyl choline?b. Which are present in a ganglioside but not in a fat?c. Which are present in sphyngomyelin and ceramides?2. (5 points) Most hormones, such as peptide hormones, exert their effect by binding to cell-surface receptors. However, steroid hormones do so by binding to cytosolic receptors. How is this possible?3. (5 points) When bacteria growing at 20C are warmed to 30C, are they more likely to synthesize membrane lipids with saturated or unsaturated fatty acids? Explain.4. (15 points) a. A research student is attempting to sequence an oligosaccharride from a mutant cell line. She finds from analysis, the presence of sialic acid (N-acetylneuraminic acid), galactose and glucose. Treatment of the intact oligo with -galactosidase has no effect, but treatment with neurominidase (which cleavaes after sialic acid) produces N-acetylneuraminic acid and a disaccharide. What is the order of sugars in this molecule?Methylation followed by hydrolysis of the disaccharide produced 2,3,6 tri-O-methyl-galactose and 2,3,4-tri-O-methyl-glucose. Draw the disaccharide that produced these results. 5. (10 points) An enzyme catalyzing the following reaction was isolated from a marine diatom. Analysis disclosed that the enzyme contained a tightly bound NAD+. Suggest a reaction mechanism for the reaction. Name the enzyme.CH2OHOHHOHHCH2O-PCH2OHHHOOHHCH2O-P6. (30 points) A principle of cellular energy metabolism is that alternative substrates arecatabolized by bringing them as quickly as possible into the mainstream glycolytic pathway. Hydroxypyruvate is such an alternative substrate. It is a 3-carbon compound with the following structure:Despite the similarity between hydroxypyruvate and pyruvate, the only cellular route by which the former can be converted into the latter is a 5-step pathway involving the 4 intermediates shown below. (The letter labels do not necessarily reflect their order in the pathway.) The pathway begins with an NADH-mediated reaction and requires both ATP and ADP, although there is no net consumption or generation of either.A B C DIn the table below, outline the pathway for conversion of hydroxypyruvate to pyruvate. Step Reaction Enzyme Coenzyme(s) Cofactor(s)1 HO-pyruvate _____2 _________3 _________4 _________5 _____ pyruvate_OOOCH2OHOOOHCH2OHH_ ___OOO-PCH2O-HHOOOHCH2O-PHOOO-PCH27. (17 points) The reaction catalyzed by phosphoglycerate kinase has a G’ of –18.8 kJ/mol. The intracellular steady state levels of the reaction components are listed below. Calculate the G for these conditions. R=8.3145 J/K.molG’ =-18.8 kJ/mol = -2.3RT log Keq’ G = G’ + 2.3RT log KQ[1,3-BPG] =10-6 M [3-PG] = 5 x 10-4 M [ATP]/[ADP] = 108. (12 points) Why is PEP so “peppy”? List at least 3 thermodynamic contributors to large free energy release upon hydrolysis.