Medical Biochemistry Exam 2 Case Studies and Multiple Choice Questions with complete solutions.

Medical Biochemistry Exam 2 Case Studies and Multiple Choice Questions with complete solutions. 2,4- Dinitrophenol (DNP), an uncoupled of oxidative phosphorylation, was used as a weight-loss agent in the 1930s. Reports of fatal overdoses led to it's discontinuation in 1939. Which of the following would most likely be true concerning individuals taking 2,4-DNP? - correct answers.ANSWER: Body temperature is elevated as a result of hypermetabolism. EXPLANATION: This is because since ATP synthesis is inhibited by this uncoupler, the energy from the proton gradient created by the electron transport chain has to go somewhere, so it is eliminated through the body as heat. Which of the following has the strongest tendency to gain electrons? - correct answers.ANSWER: Oxygen. EXPLANATION: O2 has the strongest affinity to gain electrons as it is the terminal acceptor in the electron transport chain and has the most positive reduction potential (Eo) Explain why and how the malate-aspartate shuttle moves nicotinamide adenine denuclearize reducing equivalents from the cytoskeleton to the mitochondrial matrix. - correct answers.Margaret's answer: the malate-aspartate shuttle is a part of the mitochondrial transport system. NADH from the cytosol is oxidized to NAD+ and oxaloacetate is reduced to malate. Malate is then transported across the inner mitochondrial membrane by the shuttle where it is oxidized back to OAA and NAD+ is reduced to NADH. This is due to the fact that there is no transporter for NADH across the inner mitochondrial membrane. The NADH produced by this shuttle can be oxidized by complex 1 of ETC, aka NADH dehydrogenase and generates 3 ATP. This whole process is unidirectional and costs no ATP. Carbon monoxide (CO) binds to and inhibits complex IV of the ETC. What effect, if any, should this respiratory inhibitor have on phosphorylation of adenosine diphosphate to adenosine triphosphate? - correct answers.Margaret's answer: Since complex IV of ETC is being inhibited, that means that there is no way to maintain the proton gradient, meaning there is no energy in order to phosphorylate ADP to ATP. As a reminder, complexes I and IV are proton pumping sites. Which of the following statements best describes glucose? - correct answers.It is a C-4 epimer of galactose. This is because galactose and glucose only differ in configuration around carbon 4 and are interconvertible if you use an epimerase. Glucose is a PYROSE ring in solution. A young man entered his physician's office complaining of bloating and diarrhea. His eyes were sunken, and the physician noted additional signs of dehydration. His eyes were sunken, and the physician noted additional signs of dehydration. The patient's temperature was normal. He explained that the episode had occurred following a birthday party in which he had participated in an ice-cream eating contest. the patient reported prior episodes of a similar nature following the ingestion of a significant amount of dairy products. This clinical picture is most likely due to a deficiency in the activity of: - correct answers.Lactase, as the physical symptoms suggest a deficiency in the enzyme responsible for carbohydrate degradation. The fact that it is dairy products show that the enzyme is most likely deficient in lactase. Routine examination of the urine of an asymptomatic pediatric patient showed a positive reaction with Clinitest (a copper reduction method of detecting reducing sugars) but a negative reaction with the glucose oxidase test for detecting glucose. Using this dat, which sugars could be present in the urine of this individual? - correct answers.Fructose, galactose, lactose, and xylulose could all be present in the urine of this patient, AKA not sucrose or glucose. Clinitiest is a nonspecific test that produces a change in color if urine is positive for reducing sugars (all including glucose but not sucrose). Glucose oxidase test will detect only glucose and no other sugars. The negative glucose oxidase test and a positive reducing sugar test means that glucose cannot be the reducing sugar in the urine. 1) Which one of the following statements concerning gluconeogenesis is correct? - correct answers.It is important in maintaining blood glucose during a 2-day fast. During a 2-day fast, glycogen stores are depleted and gluconeogenesis maintains blood glucose. This is an end ergo if,, aka energy-requiring pathway that occurs primarily in the liver, with the kidneys becoming major glucose producers in prolonged fasting. Since this is an end ergo if process, both ATP and GTP get hydrolyzed. Which reaction in the diagram below (pg. 124) would be inhibited in the presence of large amounts of avid in, an egg white protein that binds and sequesters biotin? - correct answers.The correct answer is the rxn of pyruvate being converted to oxaloacetate, as pyruvate is carboxylated to oxaloacetate by pyruvate carboxylase, a BIOTIN requiring enzyme.