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WorksheetsQUIZ 4
Total questions: 46
Worksheet time: 23mins
Refer to Exhibit 4A. The amino terminal amino acid is:
Arg
Cys
Gln
Met
None of these.
Refer to Exhibit 4A. The overall, net ionic charge on this peptide at pH = 7 would be:
+2
+1
0
−1
−2
Hydrogen bonds are most important in this type of structure in proteins:
primary structure
secondary structure
tertiary structure
quaternary structure
All of these
The location of prosthetic groups is shown in this level of structure:
primary structure
secondary structure
tertiary structure
quaternary structure
All of these
Covalent bonds are important in all these structures, except:
primary structure
secondary structure
tertiary structure
quaternary structure
All of these
Which of the following forces are involved in maintaining the primary structure of a protein?
covalent bonds
hydrogen bonds
ionic interactions
hydrophobic interactions
A single amino substitution can give rise to a malfunctioning protein.
True
False
What happens when a protein is denatured?
Its secondary structure is disrupted but its primary structure remains intact.
Its primary structure is disrupted but its secondary structure remains intact.
It is broken apart into its constituent amino acids.
It becomes all α-helix.
Which of the following amino acids is unlikely to be found in an α-helix?
phenylalanine
tryptophan
proline
lysine
Which of the following factors tend to destabilize α-helices?
clusters of amino acids with bulky R-groups
clusters of amino acids with similarly charged R-groups
Both of these.
Neither of these
Which of the following is true?
The peptide bonds in the β-sheet are extended.
The peptide bonds in the α-helix coil back on themselves.
Both α-helices and β-sheets can be found as part of tertiary structure.
All of these
Which of the following best describes a motif?
a repetitive supersecondary structure
a common nonrepetitive irregularity found in antiparallel β-sheets
a protein conformation with biological activity
a group of atoms other than an amino acid
Which of the following is the most common function for fibrous proteins?
enzymes
structural roles.
carrier molecules.
enzymes and carrier molecules.
All of these.
Which one is not an example of supersecondary structure?
the pyrrole ring
the Greek key
the β-meander
the β-barrel
As an animal ages, the amount of cross-linking of collagen in tissue
tends to decrease.
tends to increase.
tends to remain unchanged.
The following is true about the hydroxyproline in collagen:
Hydroxyproline is incorporated into the chain during polymerization of amino acids.
Vitamin C is necessary for the synthesis of hydroxyproline.
Hydroxyproline is important in holding the 3 strands of collagen together.
Hydroxyproline requires Vitamin C for its synthesis and it holds the collagen helix together.
All of these.
Fibrous proteins
are always composed of helical structures.
are always composed of β-sheets.
can be composed of either helical or β-sheet structures.
are always water soluble
Domains are
independently folded regions of proteins
the α-helical portions of proteins
the β-pleated regions of proteins
all of the above
Which of the following amino acid residues would most likely be found in the interior of a globular protein?
glutamic acid
lysine
leucine
serine
Disulfide bonds in proteins occur between the side chains of which of the following amino acid residues?
glutamine
lysine
cysteine
methionine
Refer to Exhibit 4B. The type of bonding labeled "O" in these figure is:
Hydrogen bonding of the peptide backbone
Covalent bonding involving the R-groups
Hydrophobic interactions
Metal ion coordination
Electrostatic attraction
Refer to Exhibit 4B. Which one shows hydrogen bonding of R-groups?
M
N
P
M and N
All of these
Refer to Exhibit 4B. Which one shows covalent bonding of R-groups?
K
L
O
K and L
All of these
X-ray crystallography is used to determine protein structure because
it can be done on dilute solutions
it requires no calculations
the positions of all atoms can be found by this method
all of these
The tertiary structure of a protein is usually a result of which of the following interactions?
intramolecular hydrogen bonding
electrostatic interactions
hydrophobic interactions
all of these
Why does myoglobin have a histidine that prevents both O2 and CO from binding perpendicularly to the heme plane?
This increases myoglobin's affinity for O2.
This increases myoglobin's affinity for CO.
This lessens the difference in myoglobin's affinity for CO versus O2.
This prevents the iron of the heme from being oxidized.
Which of the following is not true?
The heme group of myoglobin is held in place only through non-covalent bonding.
The F8 histidine is important to the function of myoglobin
The E7 histidine is important to the function of myoglobin
Myoglobin and hemoglobin differ only in one amino acid
The following bond forces are important in tertiary structure:
Disulfide bonds
Hydrogen bonds
Hydrophobic attraction
Both hydrogen bonds and hydrophobic attraction.
All of these are important in tertiary structure
Which of the following forces are involved in maintaining the quaternary structure of a protein?
hydrogen bonds
ionic interactions
hydrophobic interactions
All of these
Under normal circumstances:
Adult Hb binds to oxygen more tightly than Mb binds.
Fetal Hb binds oxygen more tightly than adult Hb.
Adult Hb binds oxygen more tightly than either fetal Hb or Mb binds.
Mb has the lowest affinity for oxygen of the 3.
More than one of these statements is correct.
Which of the following is not a characteristic of hemoglobin?
It contains two different types of subunits.
It contains a prosthetic group.
It is an allosteric enzyme.
It transports oxygen.
All of these statements are true for Hb.
In allosteric interactions
proteins that consist of a single polypeptide chain form aggregates.
disulfide bonds are broken.
changes that take place in one site of a protein cause changes at a distant site.
metal ions always bind to the protein.
Which of the following best describes what happens when hemoglobin binds bisphosphoglyceric acid (BPG)?
Binding of BPG leads to tighter binding of oxygen.
Binding of BPG allows maternal (adult) Hb to bind oxygen more tightly than fetal Hb.
Binding of BPG is important to the allosteric nature of hemoglobin
Binding of BPG causes the subunits of hemoglobin to separate.
In the Bohr effect the binding of oxygen to hemoglobin
is increased by the presence of Na+
is increased by the presence of H+ and CO2
is decreased by the presence of H+ and CO2
is unchanged
Variations in the structure of hemoglobin
do not always have an adverse effect on health
can alter the binding of heme to the protein
can occur on the surface of the protein
all of these
What would happen to hemoglobin if the BPG were removed?
It would not bind oxygen
It would dissociate into monomers
its oxygen binding curve would resemble that of myoglobin
all of the choices
Adult hemoglobin is half saturated with oxygen at what partial pressure of oxygen?
5 torr
10 torr
25 torr
50 torr
100 torr
Hydroxyurea works as a treatment for sickle cell anemia because it
causes myoglobin to act like hemoglobin
causes the body to produce fetal hemoglobin
causes hemoglobin to dissociate into monomers, thereby quadrupling the effective concentration of oxygen carrying molecules
none of the choices
What is the major force that drives nonpolar substances out of aqueous solution?
Increased enthalpy of hydrophobic bonds formed between solute molecules.
Decreased entropy of newly organized solute molecules.
Increased entropy of newly organized solute molecules.
Increased enthalpy of H-bonds in the solvent water.
Increased entropy of solvent water molecules.
The information needed for the structure of a protein is contained in
amino acid composition
primary structure
secondary structure
tertiary structure
Proteins that aid in the correct and timely folding of other proteins are called
motifs.
chaperones.
liposomes.
cooperative.
The three-dimensional shapes of proteins with biological activities are called _____.
prosthetic groups
subunits
native conformations
domains
The order in which the amino acids in a protein are linked by peptide bonds
Primary structure
Secondary structure
Domains
Tertiary structure
Quaternary structure
Specific clusters of secondary structural motifs in proteins
Primary structure
Secondary structure
Domains
Tertiary structure
Quaternary structure
The interaction of several polypeptide chains in a multisubunit protein
Primary structure
Secondary structure
Domains
Tertiary structure
Quaternary structure
_____ are spherical aggregates of lipids arranged so that the polar head groups are in contact with water and the nonpolar tails are sequestered from water.
Liposomes
Azotosomes
Escheriosomes
Chromosomes
