🧬 Biochemistry Solved MCQs with Answers

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

1490 solved MCQs

The same peptide, Val-Lys-Glu-Met-Ser-Trp-Arg-Ala. was digested with chymotrypsin to produceAnswer: Val-Lys-Glu-Met-Ser-Trp + Arg-Ala. Disulfide bonds most often stabilize the native structure ofAnswer: Extracellular proteins Secondary structure in protein refers toAnswer: Regular folding of regions of the polypeptide chain Heme is the binding pocket of myoglobin and hemoglobin and is composed ofAnswer: Hydrophobic residues What is the effect of a decrease in pH on hemoglobin oxygen affinity?Answer: Decrease in oxygen affinity What is the proportion of glycine residues in collagenous regions?Answer: One-third Which of the following statements is incorrect?Answer: Protein G contains only a-helix The oxygen binding curves of hemoglobin and myoglobinAnswer: Both (a) and (b) The nature of peptide bond can be best explained asAnswer: Partial double bond Which of the following statement is incorrect?Answer: None of the above Which hemoglobin chain replaces the beta chain in embryonic hemoglobulin?Answer: Epsilon Hemoglobin has quaternary structure and is made up ofAnswer: Four polypeptide chains, two α-chains and two β-chains When pO₂ = Kᴅ of myoglobin, the fractional saturation (Yₒ₂) is aboutAnswer: 0.5 Peptides in the fully extended chain conformationAnswer: Have Y = F = 180° The oxygen in hemoglobin and myoglobin is bound toAnswer: The iron atom in the heme group Which of the three subunits of the G proteins binds GDP and GTP?Answer: Alpha If the F and Y angles of each peptide unit in a protein are known, which of the following may also be determined?Answer: Complete secondary structure The different orders of protein structure are determined by all of the following bond types exceptAnswer: Phospho-diester bonds The heme is held in place by a bond betweenAnswer: the Fe²⁺ and histidine During the unfolding reaction of a helix, breakage of each hydrogen bond requires about 2kJ/mol. This implies hydrogen bonds areAnswer: Slightly stronger in proteins than in water If the enthalpy change for a reaction is zero, ΔG° is equal toAnswer: -TΔS° Reactions that have positive standard free energy changes (ΔGo> 0) can be made to occur in cells byAnswer: All of these The Standard Gibb's free energy, ΔG°, isAnswer: The energy required to convert one mole of reactants to one mole of products If the Standard Gibb's free energy, ΔG°, for a reaction is positive thenAnswer: The reactants will be favored The unfolding of regular secondary structure causesAnswer: Large increase in the entropy of the protein Unpaired H-bond donors and acceptors are found in the hydrophobic core of a proteinAnswer: Rarely For the unfolding reaction of Protein G, ΔH° =210.6 kJ/mol, this means thatAnswer: Folding is favored enthalpically Attractive Vander Waals forces occur betweenAnswer: Any pair of nearby atoms Which of the following forces is the most favorable for protein folding?Answer: Hydrophobic Interactions At the midpoint of a temperature transition curve,Answer: Both