🧬 Biochemistry Solved MCQs with Answers

Practice 1490 approved 🧬 Biochemistry questions with verified answers from the 🧬 Medical Science subject for Pakistan exams.

1490 solved MCQs

Which of the following is false statement with regard to comparison between Serine and HIV proteases?Answer: Both forms an acyl-enzyme intermediate In the enzyme-catalyzed reaction shown below, what will be the effect on substances A, B, C, and D of inactivating the enzyme labeled E2? A ---(E1)---> B ---(E2)---> C ---(E3)--->Answer: A and B will still be produced, but not C or D The nucleophile in serine proteases isAnswer: Both (a) and (b) The role of Asp 102 and His 57 during trypsin catalysis is toAnswer: Function as a proton shuttle The cleavage specificity of trypsin and chymotrypsin depend in part on theAnswer: Size, shape, and charge of the active site or specificity pocket The E.coli pyruvic acid dehydrogenase complex is reported toAnswer: Catalyze the oxidation of pyruvic acid to acetyl Co A and CO₂ Which of the common features are shared between serine and aspartate proteases?Answer: All of the above Before they can react, many molecules need to be destabilized. This state is typically achieved throughAnswer: The input of a small amount of activation energy Common feature in all serine proteases is aAnswer: Single reactive serine residue How is the enzyme COX-1 important in human health?Answer: It catalyzes the production of hormones that maintain the stomach lining The conformational changes from the T to the R state is initiated byAnswer: Binding of oxygen to the heme An allosteric activatorAnswer: Both (a) and (c) Bisphosphoglycerate (BPG) cannot bind to the oxygenated R state of hemoglobin becauseAnswer: Its binding pocket becomes too small to accommodate BPG The Hill coefficient (nₕ) for myoglobin and hemoglobin are respectivelyAnswer: 1.0 and 2.8 When protein binds two ligands in a non-cooperative manner, then the x-intercept of the Scatchard Plot isAnswer: 2 O₂ binding to hemoglobin results inAnswer: Both (a) and (b) In hemoglobin, allosteric effects occurAnswer: To maximize oxygen delivery to the tissues A protein that binds two ligands in a non-cooperative manner will showAnswer: Both (b) and (c) Small molecules affect hemoglobin (Hb) byAnswer: Increasing [H⁺] and decreasing Hb affinity for O₂ The specificity of a ligand binding site on a protein is based onAnswer: The amino acid residues lining the binding site Which of the following two organelles look most alike structurally?Answer: Golgi apparatus and smooth endoplasmic reticulum ER In terms of basic cell structure, what do an elephant and an oak tree have in common?Answer: All of the above Where in a eukaryotic cell, DNA can be found?Answer: Both (a) and (b) Which of the following structures is expected in a bacterium?Answer: Plasma membrane Which of the following organelles is directly connected to the outer membrane of the nucleus in a eukaryotic cell?Answer: Endoplasmic reticulum Microtubules, motor proteins, and actin filaments are all part ofAnswer: The cytoskeleton of eukaryotic cells A certain cell organelle which is made of a double phospholipid bilayer that has many large pores in it, is most likelyAnswer: The nuclear envelope Which of the following cell organelles are expected to be associated with motor proteins?Answer: Vesicles Eukaryotic cells are more efficient than prokaryotes because their internal compartmentalizationAnswer: Allows for specialization through the subdivision of particular tasks An organism's first line of defense against attack by an invader such as a virus or bacterium is usuallyAnswer: A nonspecific immune response