Chem 221 - Biochemistry for Science Majors » Fall 2021 » L6 3D Structure of Proteins Part 2 of 2
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Question #1
Ala and Leu are strong alpha-helix breakers.
A.
FALSE
B.
TRUE
Question #2
Glycine is often found in the middle of an alpha-helix.
A.
TRUE
B.
FALSE
Question #3
In the α-helix structure, the protein backbone is wound around an imaginary axis, and the R groups of the amino acid residues run parallel the axis.
A.
FALSE
B.
TRUE
Question #4
The pitch of a helix is 3.6 angstroms.
A.
TRUE
B.
FALSE
Question #5
Within an α helix, each carbonyl oxygen (residue n) of the polypeptide backbone is hydrogen-bonded to the backbone amide hydrogen of the fifth residue further toward the C-terminus.
A.
FALSE
B.
TRUE
Question #6
Each hydrogen bond in a alpha helix closes a loop containing 3.6 atoms.
A.
FALSE
B.
TRUE
Question #7
The stability of an alpha-helix is affected by the side and the identity of the side chains.
A.
TRUE
B.
FALSE
Question #8
Because of the geometry of the individual amino acids, the hydrogen bonds of an antiparallel beta sheet occur at an angle.
A.
TRUE
B.
FALSE
Question #9
Ala and Leu are strong a-helix formers.
A.
TRUE
B.
FALSE
Question #10
Antiparallel beta sheets are more stable than parallel beta sheets.
A.
FALSE
B.
TRUE
Question #11
The side chains of a beta sheet are oriented parallel to the plane of the sheet.
A.
TRUE
B.
FALSE
Question #12
Collagen, the most abundant protein in the body, is an example of what type of protein?
A.
Integral
B.
Globular
C.
Fibrous
D.
Peripheral
Question #13
β turns connect the ends of two adjacent segments of a parallel β sheet.
A.
TRUE
B.
FALSE
Question #14
Which of the following is an example of the secondary structure of a protein?
A.
Hydrogen bonding between an amine and carbonyl group
B.
Disulfide bonds between cysteine residues
C.
Hydrophobic interactions
D.
Hydrogen bonding between R groups
E.
Peptide bonding between amino acids
Question #15
What does the quaternary structure of a protein involve?
A.
the complete three-dimensional conformation
B.
partial denaturation
C.
random coil alternating with a-helix
D.
the association of two or more peptide chains
Question #16
What kinds of interactions do NOT contribute to the tertiary protein structure?
A.
peptide bonds
B.
hydrogen bonds
C.
salt bridges
D.
disulfide bridges
E.
Van der Waals interactions
Question #17
Which of the following properties of a protein is least likely to be affected by changes in pH?
A.
Net charge
B.
Primary structure
C.
Secondary structure
D.
Tertiary structure
Question #18
A structure that has hydrogen bonds between polypeptide chains arranged side by side is
A.
tertiary structure
B.
beta sheet
C.
primary structure
D.
alpha helix
Question #19
The term "denaturation," when used in conjunction with proteins or nucleic acids, refers to a change in structural characteristics primarily due to __________.
A.
the disruption of non-covalent bonds
B.
changes in primary structure
C.
the binding of toxic compounds
D.
the disruption of covalent bonds
Question #20
Disulfide bonds in a protein chain connect ________.
A.
tryptophan and alanine residues
B.
two asparagine residues
C.
an amine and a carboxylic acid group
D.
two cysteine residues
E.
an alcohol and a carboxylic acid group
Question #21
In the β-pleated sheet secondary structure of a protein, two or more amino acid sequences in separate parts of the protein are held together ________.
A.
in a coil, by hydrogen bonding
B.
by hydrogen bonding between different sections of the polypeptide chain
C.
in a triple helix
D.
in a double helix
E.
in random order, due to hydrophobic interactions
Question #22
Disulfide bonds exist only in tertiary and quaternary structures.
A.
FALSE
B.
TRUE
Question #23
The primary structure of a protein chain is
A.
determined by the side chains
B.
determined by the types of bonds it contains
C.
the overall shape of the protein
D.
the order of amino acids
E.
the arrangement of the chain in the long molecule
Question #24
An acid can denature a protein by ________.
A.
disrupting hydrophobic interactions within a protein chain
B.
removing helping molecules such as heme
C.
breaking disulfide bridges
D.
disrupting salt bridges between side chains
E.
agitating the protein chains
Question #25
Heavy metals denature proteins by ________.
A.
disrupting disulfide bonds
B.
releasing amino acids
C.
disrupting salt bridges
D.
changing the temperature of the protein solution
E.
disrupting hydrophobic interactions
Question #26
Detergents denature proteins by interfering with the hydrophobic interactions in the proteins structure
A.
TRUE
B.
FALSE
Question #27
Reducing agents disrupt the hydrogen bonds.
A.
FALSE
B.
TRUE
Question #28
Heat increases the kinetic energy and causes the molecules to vibrate so rapidly and violently that the covalent interactions are disrupted.
A.
FALSE
B.
TRUE
Question #29
Since denaturation reactions are not strong enough to break the peptide bonds, the primary structure (sequence of amino acids) remains the same after a denaturation process.
A.
FALSE
B.
TRUE
Question #30
The attractive forces that are important in the secondary structure of a protein are ________.
A.
salt bridges
B.
disulfide bonds
C.
peptide bonds
D.
hydrophobic interactions
E.
hydrogen bonds
Question #31
The analysis of a protein for its amino acid content is valuable in determining the protein's
A.
tertiary structure
B.
main structure
C.
quaternary structure
D.
primary structure
E.
secondary structure
Question #32
A disulfide bond, also called an S-S bond, or disulfide bridge, is a covalent bond derived from two thiol groups.
A.
FALSE
B.
TRUE
Question #33
A protein with a quaternary structure has multiple subunits.
A.
TRUE
B.
FALSE
Question #34
The pitch of a helix contains 3.6 amino acids.
A.
FALSE
B.
TRUE
Question #35
Tertiary structure arises from the interaction of amino acids that are close by in the primary structure.
A.
FALSE
B.
TRUE
Question #36
Fibrous proteins are typically soluble in water.
A.
TRUE
B.
FALSE
Question #37
In an alpha helix, all of the H bonds lie parallel to the helix axis and all of the carbonyl groups are pointing in one direction along the helix axis while the N-H groups are pointing in the opposite direction.
A.
FALSE
B.
TRUE
Question #38
When a protein has two or more polypeptide subunits, their arrangement in space is referred to as quaternary structure.
A.
TRUE
B.
FALSE
Question #39
Which of the following is not a component of tertiary structure?
A.
Hydrophobic interactions
B.
Ionic bonds
C.
Disulfide bonds
D.
Hydrogen bonds
E.
Interactions between two or more sub-units
Question #40
2-mercaptoethanol is a chemical agent used in denaturing proteins. Its primary method of denaturing involves separating disulfide bonds. Based on this method of denaturation, what is the lowest level of protein structure affected by 2-mercaptoethanol?
A.
Secondary structure
B.
Tertiary structure
C.
Primary structure
D.
Quaternary structure
Question #41
The only amino acid that can form disulfide bonds is methionine
A.
FALSE
B.
TRUE
Question #42
A beta-sheet is formed by hydrogen bonding between the hydrogen of an amine group and the backbone carbonyl group.
A.
FALSE
B.
TRUE
Question #43
Within the α helix, the atoms of peptide bonds participates in hydrogen bonding.
A.
TRUE
B.
FALSE
Question #44
The α helix and beta sheet are examples of ___________structures
A.
Secondary
B.
Primary
C.
Tertiary
D.
Quaternary
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