Electron Transport Chain Features and Mitochondrial Proton Pumping

1. BCHM2072/2972 2004 THEORY PAPER MCQs Qs 11 - 20

2. 11. ALL the facts listed below are features of the electron transport chain. Which feature is NOT RELEVANT to the process of proton pumping from the mitochondrial matrix? A. In each Complex there are proteins which have electron or hydrogen-carrying prosthetic groups B. The Complexes are free to move laterally in the inner mitochondrial membrane C. Some Complexes span the membrane D. In some redox reactions in the chain, protons are consumed E. The inter-complex carriers ubiquinione and cytochrome c carry hydrogens and electrons, respectively R I R R R

3. As a check on the scanning procedure, enter an answer of A to question 12 on the answer sheet Not this year

4. 13. Which statement regarding the F0F1ATPase is INCORRECT? A. The flow of protons through F0 is required to turn the gamma-subunit B. The alpha- and beta-subunits of F1 DO NOT rotate as protons enter the matrix C. The F1 portion is located on the matrix face of the inner mitochondrial membrane D. ATP is made by the gamma-subunits E. About three protons are required to make one ATP T T T F T

5. 14. Which statement regarding leptin is INCORRECT? A. Obese individuals are relatively resistant to the actions of leptin B. Leptin increases energy expenditure in rodents but not so much in humans C. Leptin is secreted by the alpha-cells of the pancreas after a meal D. A lack of leptin induces hyperphagia E. Blood leptin levels are generally higher in obese individuals T T F T T

6. 15. Which statement about Basal Metabolic Rate (BMR) is CORRECT? A. BMR never comprises more than 30% of whole body energy expenditure B. BMR refers to the energy used as a consequence of GLUT-1 catalysed glucose metabolism C. BMR is the average daily amount of energy expended by a standard 70 kg person at 20oC D. BMR is decreased in response to thyroid hormone E. BMR is lower in obese subjects than in lean subjects of the same weight F F F F T

7. 16. Which of the following statements regarding the Glycemic Index (GI) is CORRECT? A. Amylose starch has a higher GI than amylopectin starch B. Sucrose does not have a GI because it is a disaccharide containing fructose C. It is not practical to measure the GI of foods containing less than 1% (w/w) carbohydrate D. The GI of lactose is 100 E. High GI foods often cause flatulence F F T F F

8. Opposite is the structure of glucose presented as a Haworth projection. Consider this structure and the structures A-E:

9. Which structure (A-E) is a keto sugar? • Which structure (A-E) is the non-enzymic product of -D-glucose in solution? B C

10. 19. Which of the facts below is NOT an important reason why the concentration of blood glucose needs to be kept at approximately 5 mM? A. The skin, red blood cells and kidney have an obligatory requirement for glucose B. The extent of protein glycosylation is directly proportional to time of exposure to glucose C. The glycosylation of proteins is a non-enzymatically controlled reaction D. Glucose is a relatively reactive molecule E. The brain does not possess GLUT-4 transporters: it only has GLUT-1 transporters I I I I N

11. 20. Which of the following does NOT have a free anomeric carbon atom? A. Amylose B. Sucrose C. Maltose D. Lactose E. Cellulose Has Not Has Has Has