Biochemistry

Factor H, a complement regulatory protein in plasma, binds C3b and (A) competes with factor B to displace Bb from convertase. (B) initiates the catabolism of C3b into inactive products. (C) then binds to C3bBb convertase. (D) acts as a cofactor for factor I.  

Which one or more of the following statements correctly describe(s) the changes upon the addition of puromycin during eukaryotic translation? (A) Puromycin resembles the aminoacyl end of the charged tRNA. (B) Puromycin occupies the A site of the translating ribosomes. (C) Puromycin occupies the P site of the translating ribosomes. (D) Puromycin occupies the E … Read more

Which one or more of the following statements is/are correct in the processing of pre-mRNA in eukaryotes? (A) 3′ → 5′ exonuclease activity is involved in the conversion of pre-mRNA to mRNA. (B) 5′-capping and addition of 3′-poly A tail precede splicing. (C) Splicing of pre-mRNA occurs via transesterification reaction. (D) Alternative splicing can yield … Read more

Which one or more of the following statements correctly describe(s) fluorescence spectroscopy? (A) The emission maxima (λmax) is independent of the excitation wavelength. (B) The emission maxima (λmax) depends on the concentration of a quencher. (C) The emission maxima (λmax) varies with solvent polarity. (D) The emission maxima (λmax) varies with temperature.

Which one or more of the following statements is/are correct regarding the transport and retention of proteins in different cell organelles? (A) Mannose 6-phosphate residues are involved in targeting proteins to lysosomes. (B) Transport of proteins into the mitochondrial compartment is aided by positively charged amino acid residues at the N-terminus and internal hydrophobic segments. … Read more

Which one or more of the following statements is/are correct regarding the electromotive force generated by the electron transfer chain? (A) It is used for the synthesis of ATP. (B) It is not used for active transport processes. (C) It includes a pH gradient component. (D) It does not include an electrical potential gradient component.

Which one of the following is the correct match between the molecular properties listed in Column I and the corresponding biochemical separation methods in Column II? Column I Column II P. Solubility i. Reverse phase chromatography Q. Ionic charge ii. Ultracentrifugation R. Polarity iii. Salting out S. Molecular size iv. Isoelectric focusing v. Gel electrophoresis … Read more

Metabolic intermediates provide the backbone for the synthesis of amino acids. Match the metabolic intermediates listed in Column I with their corresponding amino acids given in Column II. Column I Column II P. α-Ketoglutarate i. Histidine Q. Ribose 5-phosphate ii. Glutamate R. 3-Phosphoglycerate iii. Aspartate S. Phosphoenolpyruvate iv. Phenylalanine v. Serine (A) P-ii; Q-i; R-v; … Read more

If a 10 mM solution of a biomolecule in a cuvette of path length 10 mm absorbs 90% of the incident light at 280 nm, the molar extinction coefficient of the biomolecule at this wavelength is _____________ M⁻¹cm⁻¹.  

In a lactic acid solution at pH 4.8, the concentrations of lactic acid and lactate are 0.01 M and 0.087 M, respectively. The calculated pKa of lactic acid is ________.