MCQOPTIONS
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MCQOPTIONS
This section includes 29 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
When = of myoglobin, the fractional saturation (Y) is about |
| A. | 0.1 |
| B. | 0.5 |
| C. | 0.9 |
| D. | 1.7 |
| Answer» C. 0.9 | |
| 2. |
Hemoglobin has quaternary structure and is made up of |
| A. | six polypeptide chains, two -chains and four -chains |
| B. | two polypeptide chains, one -chains and one -chains |
| C. | four polypeptide chains, two -chains and two -chains |
| D. | five polypeptide chains, two -chains and three -chains |
| Answer» D. five polypeptide chains, two -chains and three -chains | |
| 3. |
When pO2 = Kd of myoglobin, the fractional saturation (YO2) is about |
| A. | 0.1 |
| B. | 0.5 |
| C. | 0.9 |
| D. | 1.7 |
| Answer» C. 0.9 | |
| 4. |
Peptides in the fully extended chain conformation |
| A. | have Y = F = 180 |
| B. | do not occur in nature |
| C. | also have a cis geometry in their peptide bonds |
| D. | are equivalent to the (3-sheet structure |
| Answer» B. do not occur in nature | |
| 5. |
The oxygen in hemoglobin and myoglobin is bound to |
| A. | the iron atom in the heme group |
| B. | the nitrogen atoms on the heme |
| C. | histidine residues in the protein |
| D. | lysine residues in the protein |
| Answer» B. the nitrogen atoms on the heme | |
| 6. |
An oil drop with a polar coat is a metaphor referring to the three dimensional structure of |
| A. | fibrous proteins |
| B. | collagen |
| C. | globular proteins |
| D. | silk protein |
| Answer» D. silk protein | |
| 7. |
What was the first protein whose complete tertiary structure was determined? |
| A. | Lysozyme |
| B. | Myoglobin |
| C. | Pancreatic ribonuclease |
| D. | Pancreatic DNase |
| Answer» C. Pancreatic ribonuclease | |
| 8. |
In the -pleated sheet |
| A. | hydrogen bonds are formed between the peptide bonds |
| B. | adjacent polypeptide chains can either be parallel or antiparallel |
| C. | the polypeptide chain is fully extended |
| D. | all of the above |
| Answer» E. | |
| 9. |
The Ramachandran Plot illustrates the fact that |
| A. | the peptide bond is planar |
| B. | the F & Y angles can assume any value in a peptide |
| C. | the F & Y angles can assume only a single value in a protein |
| D. | the F & Y angles can assume approximately three different values |
| Answer» E. | |
| 10. |
The resonance structures that can be drawn for the peptide bond indicate that the peptide bond |
| A. | is stronger than an ordinary single bond |
| B. | has partial double bond character |
| C. | both (a) and (b) |
| D. | is still not completely understood |
| Answer» D. is still not completely understood | |
| 11. |
The major element of secondary structure in myoglobin and hemoglobin is |
| A. | the P-strand |
| B. | the a-helix |
| C. | the reverse turn |
| D. | All of these |
| Answer» C. the reverse turn | |
| 12. |
The same peptide, Val-Lys-Glu-Met-Ser-Trp-Arg-Ala. was digested with chymotrypsin to produce |
| A. | Val-Lys + Glu-Met-Ser + Trp-Arg-Ala. |
| B. | Val-Lys-Glu-Met-Ser-Trp + Arg-Ala. |
| C. | Val-Lys-Glu-Met-Ser + Trp-Arg-Ala. |
| D. | Val-Lys-Glu-Met + Ser-Trp-Arg-Ala. |
| Answer» C. Val-Lys-Glu-Met-Ser + Trp-Arg-Ala. | |
| 13. |
Which of the three subunits of the G proteins binds GDP and GTP? |
| A. | Alpha |
| B. | Beta |
| C. | Gamma |
| D. | Delta |
| Answer» B. Beta | |
| 14. |
Disulfide bonds most often stabilize the native structure of |
| A. | extracellular proteins |
| B. | dimeric proteins |
| C. | hydrophobic proteins |
| D. | intracellular proteins |
| Answer» B. dimeric proteins | |
| 15. |
What is the effect of a decrease in pH on hemoglobin oxygen affinity? |
| A. | Decrease in oxygen affinity |
| B. | Increase in oxygen affinity |
| C. | No effect on oxygen affinity |
| D. | Increase affinity in muscle cell otherwise decrease |
| Answer» B. Increase in oxygen affinity | |
| 16. |
What is the proportion of glycine residues in collagenous regions? |
| A. | One-fourth |
| B. | One-third |
| C. | Half |
| D. | One-tenth |
| Answer» C. Half | |
| 17. |
Which hemoglobin chain replaces the beta chain in embryonic hemoglobulin? |
| A. | Delta |
| B. | Epsilon |
| C. | Gamma |
| D. | Alfa |
| Answer» C. Gamma | |
| 18. |
Secondary structure in protein refers to |
| A. | linear sequence of amino acids joined together by peptide bond |
| B. | three dimensional arrangement of all amino acids in polypeptide chain |
| C. | regular folding of regions of the polypeptide chain |
| D. | protein made up of more than one polypeptide chain |
| Answer» D. protein made up of more than one polypeptide chain | |
| 19. |
Heme is the binding pocket of myoglobin and hemoglobin and is composed of |
| A. | negatively charged residues |
| B. | polar residues |
| C. | hydrophobic residues |
| D. | positively charged residues |
| Answer» D. positively charged residues | |
| 20. |
Hydrogen bonds in a-helices are |
| A. | more numerous than Vander Waals interactions |
| B. | not present at Phe residues |
| C. | analogous to the steps in a spiral staircase |
| D. | roughly parallel to the helix axis |
| Answer» E. | |
| 21. |
Which of the following is an example of tertiary structure in a protein? |
| A. | A multimeric protein |
| B. | An a-helix |
| C. | A P-pleated sheet |
| D. | A globular domain |
| Answer» E. | |
| 22. |
The peptide, Val-Lys-Glu-Met-Ser-Trp-Arg-Ala, was digested with cyanogen bromide (CNBr) to produce: |
| A. | Val-Lys + Glu-Met-Ser + Trp-Arg-Ala |
| B. | Val-Lys-Glu-Met-Ser-Trp + Arg-Ala |
| C. | Val-Lys-Glu-Met + Ser-Trp-Arg-Ala |
| D. | Val-Lys-Glu + Met-Ser-Trp-Arg-Ala |
| Answer» D. Val-Lys-Glu + Met-Ser-Trp-Arg-Ala | |
| 23. |
The peptide bond in proteins is |
| A. | only found between proline residues |
| B. | usually cis unless proline is the next amino acid |
| C. | usually trans unless proline is the next amino acid |
| D. | is planar because of steric hinderance |
| Answer» D. is planar because of steric hinderance | |
| 24. |
The different orders of protein structure are determined by all of the following bond types except |
| A. | peptide bonds |
| B. | phospho-diester bonds |
| C. | disulfide bridges |
| D. | hydrogen bonds |
| Answer» C. disulfide bridges | |
| 25. |
In deoxy hemoglobin (Hb), the Fe (II) is coordinated to |
| A. | four nitrogens of heme, the proximal His, and a water molecule |
| B. | four nitrogens of heme and to a water molecule |
| C. | two nitrogens of heme and to three His residues in Hb |
| D. | two nitrogens of heme and to three water molecules |
| Answer» B. four nitrogens of heme and to a water molecule | |
| 26. |
In -pleated sheet structures neighbouring |
| A. | chains lie in a flat plane |
| B. | neighboring residues are hydrogen bonded |
| C. | neighboring chains are connected by a-helices |
| D. | neighboring chains are hydrogen bonded |
| Answer» E. | |
| 27. |
The nature of peptide bond can be best explained as |
| A. | partial double bond |
| B. | truly double bond |
| C. | Hydrogen bond |
| D. | Van der waals force |
| Answer» B. truly double bond | |
| 28. |
The oxygen binding curves of hemoglobin and myoglobin |
| A. | allow maximum transfer of oxygen to the tissues |
| B. | are a consequence of the quaternary structure of hemoglobin |
| C. | both (a) and (b) |
| D. | are identical |
| Answer» D. are identical | |
| 29. |
If the F and Y angles of each peptide unit in a protein are known, which of the following may also be determined? |
| A. | Complete secondary structure |
| B. | Complete tertiary structure |
| C. | Complete quaternary structure |
| D. | Thermodynamic stability |
| Answer» B. Complete tertiary structure | |