biochemistry Unit 1 Test Latest Update
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Which of the following amino acid would not be commonly found in the middle of a an α-
helical domain? -correct answerProline.
It is considered a 'helix breaker' and would not be found in an alpha helix; all other
residues are nonpolar hydrophobic and could reside in a transmemebrane domain.
Changes in the physiological variables listed below can alter the affinity of hemoglobin
for oxygen. Which of the following will lower the affinity of hemoglobin for oxygen?
a) decrease in protons
b) increase in 2,3 bisphosphoglycerate (BPG)
c) increase in pH
d) decrease in CO2 -correct answerIncrease in 2,3 bisphosphoglycerate (BPG)
A 22-year old female presents to the emergency department with acute abdominal pain.
She indicates the pain came on rapidly in her mid-abdominal region. She has vomited
,several times over the last 4 hours. A diagnosis of acute pancreatitis is made and she is
rushed to surgery. Elevation of which of the following serum enzymes would be
consistent with this diagnosis? -correct answerAmylase
Which of the following is the best description of primary protein structure? -correct
answerA newly synthesized strand of amino acids
Cleavage of fructose 1, 6-bisphosphate to dihydroxyacetone and glyceraldehyde 3-
phosphate is achieved by what class of enzymes? -correct answerLyase
Which of the following amino acid would not be commonly found in the middle of a an α-
helical domain? -correct answerProline
Domains are common structural elements that retain a particular function within the
protein. Which of the following is an example of a protein domain?
a) a prosthetic group such as heme
b) irregular coils and loops
c) an arrangement of β-strands connected by α- helixes
d) a single α- helix -correct answerAn arrangement of β-strands connected by α-
helixes
α helices and β sheets are primarily stabilized by which of the following interactions? -
correct answerhydrogen bonding
Hydrogen bonding is the primary stabilizing force in both secondary structures. In alpha
helices the hydrogen bond is between the carbonyl oxygen group from one peptide
bond and that amide hydrogen from a different peptide bond approximately amide 4
resides down in the helix. In beta sheets, the hydrogen bonding is between the carbonyl
oxygen and the amide hydrogen from different peptide strands.
Compare and contrast beta sheets and alpha helical formations. (Figure 7.3 vs. 7.5)
Phosphorylation of an amino acid changes the charge on the residue to: -correct
answerNegative
The addition of a phospho group will add a large negative moiety to the amino acid and
change the functionality of the protein.
Which of the following amino acid would not be commonly found in the middle of a an α-
helical domain? -correct answerProline
A 55-year old man is brought to the emergency room with a chief complaint of chest
pain and tingling in his left arm. Elevation of which of the following enzymes in
circulation would be most indicative of a myocardial infarction? -correct
answerTroponin
,A 22-year-old female is diagnosed with acute pancreatitis. Elevation of which of the
following serum enzymes would be consistent with this diagnosis?
a) lactate dehydrogenase
b) amylase
c) troponin
d) creatine kinase -correct answeramylase
Hemoglobin binds oxygen with a greater affinity in the: -correct answerR-State ---
Hemoglobin binds oxygen with a greater affinity in the R state. As oxygen binds each
subunit, the affinity for oxygen increases; this is termed cooperative binding.
A 19-year-old boy is diagnosed with Creutzfeldt-Jakob Disease which is caused by the
introduction of an amyloid fold in the disease-causing protein. The introduction of this
fold causes the protein to transition from a primarily α-helical structure to an aggregate
of mostly β-sheets. This change in protein structure (leading to disease) is best
attributed to changes in which of the following? -correct answerFolding of the
secondary structures
α-helices and β-sheets are primarily stabilized by which of the following interactions -
correct answerHydrogen bonding
Movement of ammonia from an amino acid to an alpha-keto acid involves a family of
enzymes best categorized as:
a) transferases
b) ligases
c) lyases
d) isomerases -correct answertransferases
Which of the following proteins is likely to have quaternary structure?
a) a protein that contains both α-helix and β-sheet secondary structures
b) a multimeric protein that contains multiple peptide chains
c) a small protein consisting of a single amino acid chain
d) a large transmemberane protein with seven alpha helical domains -correct answera
multimeric protein that contains multiple peptide chains
A decrease in blood pH from 7.0 to 6.0 would be accompanied by which of the following
changes in ion concentration? -correct answerA 10-fold increase in hydrogen ion
concentration-
Explanation: The pH is the negative log of the hydrogen ion concentration, [H+]. At a pH
of 7.0 [H+] is 10-7; and at pH 6.0[H+] is 10-6. The [H+] has changed by a factor of 10-
6/10-7 which is 10. A decrease in 1 pH units is a 10 fold increase in [H+]
, Cleavage of fructose 1, 6-bisphosphate to dihydroxyacetone and glyceraldehyde 3-
phosphate is achieved by what class of enzymes? -correct answerLyase
A 55-year old man is brought to the emergency room with a chief complaint of chest
pain and tingling in his left arm. Elevation of which of the following enzymes in
circulation would be most indicative of a myocardial infarction? -correct
answerTroponin
Which of the following is the best description of primary protein structure? -correct
answerA newly synthesized strand of amino acids
Discriminate between primary, secondary, tertiary, and quaternary protein structure
(Overview Figure 7.1)
Hemoglobin bound to heme is termed a holoprotein. The heme or porphyrin ring is
required for oxygen binding and it is defined as which of the following? -correct
answerProsthetic group
An enzyme has a mutation within the substrate binding site that reduces the binding of
the coenzyme needed for covalent catalysis. Which of the following is likely to result as
a consequence of this mutation? -correct answerThe enzyme will not be able to form
the transition state complex
Cleavage of fructose 1, 6 bisphosphate to dihydroxyacetone and glyceraldehyde 3-
phosphate is achieved by what class of enzymes?
a) ligase
b) lyase
c) transferase
d) hydrolase -correct answerLyase
Hemoglobin bound to heme is termed a holoprotein. The heme or porphyrin ring is
required for oxygen binding and it is termed a: -correct answerprosthetic group
Hemoglobin or myoglobin bound to the heme prosthetic group is termed a holoprotein.
Without the heme the protein is termed an apoprotein.
Describe the structural difference between hemoglobin and myoglobin and compare O2
binding properties of hemoglobin and myoglobin (Figure 7.10 and 7.11)
Which of the following is the best description of primary protein structure? -correct
answerA newly synthesized strand of amino acids
Allosteric activators of hemoglobin will increase enzyme activity through which of the
following mechanisms? -correct answerBinding the enzyme, and keeping it in the "R"
conformation