Med Biochem 2 - Weeks 1-6 (for midsem exam) Questions And Answers 2023 A+

Med Biochem 2 - Weeks 1-6 (for midsem exam) Questions And Answers 2023 A+ Topic 2 What are the 2 energy products of glycolysis? - ANS-ATP & NADH Topic 2 True/false Glycolysis itself is aerobic, but immediately upon finishing, the cell continues respiration either aerobically or anaerobically depending on what it needs - ANS-False Glycolysis itself is ANAEROBIC, but immediately upon finishing, the cell continues respiration either aerobically or anaerobically depending on what it needs Topic 2 Glycolysis has 2 phases, what are these? Also, what is the major difference between the pathways? - ANS-1. Prepatory phase 2. Payoff phase The main difference is that energy is produced in the payoff phase, whereas 2x ATP are used in the prepatory phase with no energy payoff True/false The cytoplasm within a cell is a reductive environment - ANS-True Topic 2 For every one molecule of glucose, how many pyruvate molecules are produced? - ANS-1 glucose: 2 pyruvate Week 2 tut question 1 (a) Name whether the following compounds are low or high energy phosphate compounds glyceraldehyde-3-phosphate 1, 3-bisphosphate Phosphoenolpyruvate (b) Explain the intermediate position of the ATP/ADP system as in the scale of high energy phosphate compounds. - ANS-glyceraldehyde-3-phosphate LOW ENERGY 1, 3-bisphosphoglycerate HIGH ENERGY Phosphoenolpyruvate SUPER HIGH ENERGY Energetically speaking, the flow of energy is from high energy (less stable) to low energy (more stable). The reason compounds of higher energy than ATP are present is to make ADP phosphorylation an energetically favourable process. Week 2 tut question Question 2 Yeast is a single celled eukaryote which can be manipulated to alter the cellular concentrations of certain compounds. Explain the effect on glycolysis of the following changes in the intracellular concentrations of some glycolytic intermediates and some glycolytic enzymes. a) What happens to the flow of carbon through the glycolytic pathway if inorganic phosphate (Pi) is removed from the cell? b) Which, if any, glycolytic intermediate either builds up or is depleted in the cell under conditions of low inorganic phosphate? - ANS-a) Assume that glucose and all other glycolytic intermediates are present and all glycolytic enzymes are present. Inorganic phosphate is required during the oxidation step of glycolysis. If Pi is removed, the flow of carbon through the pathway would cease and the cell would be unable to produce ATP via this mechanism. In the absence of another energy-yielding pathway the cell would die. b) In low Pi conditions, [glyceraldehyde-3-phosphate] would build up causing a shift in the equilibrium between G-3-P and DHAP. Since this reaction is before the pay off phase, no ATP would be produced thus ATP in the cell would be depleted. Higher [DHAP] may be shunted off towards fatty acid production. Week 2 tut question Question 3 a) Write a balanced equation for all the reactions in the catabolism glucose in the preparation and pay off phase of glycolysis. b) Write the overall (net equation) for the preparation and pay off phases for glycolysis. - ANS-a) Preparation Phase: Glucose + ATP Glucose-6-P + ADP Glucose-6-P Fructose-6-P Fructose-6-P + ATP Fructose-1,6-bisphosphate + ADP Fructose-1,6-bisphosphate Glyceraldehyde-3-P + dihydroxyacetone phosphate + NADH + H+ [ dihydroxyacetone phosphate Glyceraldehyde-3-P ] Payoff Phase: 2 Glyceraldehyde-3-P + NAD+ + 2Pi 1,3-bisphosphoglycerate + NADH + H+ CONTINUES...