Bioenergetics — DU B. Sc. (Hons) Biochemistry Previous Year Question Papers

(b) Write short notes on the following : 5. Give the mechanism of the following: (a) Bacteriorhodopsin as a light driven proton pump. (b) Light driven water splitting in chloroplast. (c) Scavenging of reactive oxygen species in (5,5,5) 6. Give the biological role of the following (any three): (a) Alternative respiratory pathways in skunk cabbage. (b) Thermogenin protein in new born mammals. (c) Adenine nucleoside translocase in mitochondria. (d) Malate shuttle in mitochondria. (3x5=15) 1. (a) Explain the following terms (any six): (ii) Redox potential (iii) Energy charge of the cell (iv) Hills reaction (v) State function (vi) Activation energy (vii) Open system (vili) Accessory pigments (b) Give the contribution of the following Scientist: (i) Albert L. Lehninger (i) Paul Boyer (iii) Peter Mitchell (12,3) 2. (a) Give the basis of high energy of hydrolysis of the following molecules : (i) 1,3-bis phosphoglycerate (ii) Phosphoenol pyruvate (b) Write a short note on universal electron carriers. (c) The E'° values for the NAD+/NADH and pyruvate/lactate conjugate redox pairs are -0.32 V and -0.19 V, respectively. (i) Which redox pair has the greater tendency to lose electrons, Justify? (i) Which pair is the stronger oxidizing agent, (iti) Beginning with 1 M concentrations of each reactant and product at pH 7 and 25°C, in which direction will the following reaction proceed NADH + Ht + Pyruvate → Lactate + NAD+ (iv) What is the standard free-energy change (AG°') for the conversion of pyruvate to lactate? (4,4,7) 3. (a) Give the site of inhibition of the following inhibitors of electron transport chain : (b) Draw the structural model of Fo-Fl ATP synthase. Give the binding change mechanism of ATP synthesis. (c) Calculate the proton motive force generated across the inner mitochondrial membrane per pair of electrons transferred through the respiratory chain from NADH to 02. Assume A' is 0.20 V and pH difference is 0.25 units. (R=8.314 J/mol.K and (d) Schematically outline the electron transport from NADH to molecular oxygen via the respiratory chain. 4. (a) Differentiate between the following : (i) PSI and PSII. (ii) Electron transport in Green sulfur bacteria and Purple Photosynthetic bacteria.