Structure and Properties of Peptides MCQs : This section focuses on the "Structure and Properties of Peptides". These Multiple Choice Questions (MCQs) should be practiced to improve the Structure and Properties of Peptides skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
When pO2 = Kd of myoglobin, the fractional saturation (YO2) is about
A. 0.1
B. 0.5
C. 0.9
D. 1.7
Question 2
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
Question 3
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
Question 4
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
Question 5
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
Question 6
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
Question 7
The molecular formula for glycine is C2H5O2N. What would be the molecular formula for a linear oligomer made by linking ten glycine molecules together by condensation synthesis?
A. C20H50O20N10
B. C20H32O11N10
C. C20H40O10N10
D. C20H68O29N10
Question 8
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
Question 9
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
Question 10
Which of the following statements is incorrect?
A. Protein G contains both a-helix and P-sheet
B. Protein G contains only a-helix
C. Fatty acid binding protein contains largely P-sheet
D. Hemoglobin contains four sub-units
Question 11
Hemoglobin has quaternary structure and is made up of
A. six polypeptide chains, two α-chains and four β-chains
B. two polypeptide chains, one α-chains and one β-chains
C. four polypeptide chains, two α-chains and two β-chains
D. five polypeptide chains, two α-chains and three β-chains
Question 12
Which hemoglobin chain replaces the beta chain in embryonic hemoglobulin?
A. Delta
B. Epsilon
C. Gamma
D. Alfa
Question 13
Which of the three subunits of the G proteins binds GDP and GTP?
A. Alpha
B. Beta
C. Gamma
D. Delta
Question 14
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
Question 15
What is the proportion of glycine residues in collagenous regions?
A. One-fourth
B. One-third
C. Half
D. One-tenth
Question 16
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
Question 17
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
Question 18
Disulfide bonds most often stabilize the native structure of
A. extracellular proteins
B. dimeric proteins
C. hydrophobic proteins
D. intracellular proteins
Question 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
Question 20
Which of the following statement is incorrect?
A. Hemoglobin and myoglobin are the two oxygen binding proteins
B. Hemoglobin transports O2 in the blood
C. Myoglobin stores O2 in muscles
D. None of the above
Question 21
In β-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
Question 22
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
Question 23
The peptide bond in proteins is
A. planar, but rotates to three preferred dihedral angles
B. nonpolar, but rotates to three preferred dihedral angles
C. nonpolar, and fixed in a trans conformation
D. planar, and usually found in a trans conformation
Question 24
What was the first protein whose complete tertiary structure was determined?
A. Lysozyme
B. Myoglobin
C. Pancreatic ribonuclease
D. Pancreatic DNase
Question 25
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
Question 26
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
Question 27
The heme is held in place by a bond between
A. the Fe2+ and cysteine
B. the Fe3+ and histidine
C. the Fe3+ and cysteine
D. the Fe2+ and histidine
Question 28
In the β-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
Question 29
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
Question 30
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
Question 31
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
Question 32
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
Question 33
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.