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Which of the following amino acid would not be commonly found in the middle of a an α-helical domain? .....answer.....Proline.
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 .....answer.....Increase 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? .....answer.....Amylase
Which of the following is the best description of primary protein structure? .....answer.....A 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? .....answer.....Lyase
Which of the following amino acid would not be commonly found in the middle of a an α-helical domain? .....answer.....Proline
Domains are common structural elements that retain a particular function within the protein. Which of the following is an example of a protein domain?
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? .....answer.....Proline
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? .....answer.....Troponin
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 .....answer.....amylase
Hemoglobin binds oxygen with a greater affinity in the: .....answer.....R-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? .....answer.....Folding of the secondary structures
α-helices and β-sheets are primarily stabilized by which of the following interactions .....answer.....Hydrogen 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 .....answer.....transferases
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? .....answer.....Troponin
Which of the following is the best description of primary protein structure? .....answer.....A 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? .....answer.....Prosthetic 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? .....answer.....The 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 .....answer.....Lyase
Hemoglobin bound to heme is termed a holoprotein. The heme or porphyrin ring is required for oxygen binding and it is termed a: .....answer.....prosthetic 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. and 7.11)
Which of the following is the best description of primary protein structure? .....answer.....A newly synthesized strand of amino acids
d) pyridoxal phosphate .....answer.....pyridoxal phsophate
Domains are common structural elements that retain a particular function within the protein. Which of the following is an example of a protein domain? .....answer.....An arrangement of β-strands connected by α-helices (βαβαβ)
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? .....answer.....The enzyme will not be able to form the transition state complex
Aspartate is classified as a: .....answer.....charged amino acid
Aspartate (asp,D) is negatively charged and therefore acidic.
List and name the 20 amino acids that commonly occur in proteins and classify them according to polarity, size, and charge
At physiological pH (pH 7.4) carboxylic acids (COOH containing acids) are: .....answer.....approximately 100% dissociated
The pKa of most carboxylic acids is between 2 and 5, therefore at pH 7. these acids are nearly fully dissociated.
Define and explain pH, pKa, and the dissociation constant Ka
A new enzyme is discovered that increases in activity when it is phosphorylated on an exposed tyrosine residue. Phosphorylation of this amino acid is classified as which of the following? .....answer.....Covalent modification
Which of the following best describes tertiary structure?
a) interactions between differing subunits of a protein
b) interactions between α-helixes and β-pleated sheets to form a domain
c) interactions between amino acids 4 residues away from each other
d) interactions between single amino acids adjacent to one another .....answer.....interactions between α-helixes and β-pleated sheets to form a domain
In the image below the blue line indicates enzyme kinetics with no inhibitor present. Based on this information which of the following is true? .....answer.....The green line shows enzyme kinetics with the addition of a noncompetitive inhibitor
Hemoglobin bound to heme is termed a holoprotein. The heme is required for oxygen binding and is defined as which of the following?
a) apoprotein
b) holoprotein
c) heteroprotein
d) prosthetic group .....answer.....prosthetic group
The association of DNA and histones can be modified by histone acetylation. A decrease in histone acetylation will have which of the following impacts on the association of DNA and histones? .....answer.....Increase DNA: histone association
Children with cystinosis have growth delay and renal issues to to accumulation of cysteine in cellular lysosomes. The defect involves a specific
lysosomal membrane receptor that facilitates cysteine removal from the cell. An effective therapy involves administration of a drug with a similar structure to cysteine. This therapy reflects the general principle that competitive inhibitors typically resemble the structure of which of the following?
a) substrates or ligands that bind the active site
b) enzyme or receptor protein
c) enzyme reaction products
d) the cofactor .....answer.....substrates or ligands that bind the active site
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. Laboratory tests illustrate elevated levels of amylase. This result would indicate a dysfunction in which of the following organs?
a) Pancreas
b) Heart
c) Liver
d) Muscle .....answer.....a
Use the figure below to compare the activities of glucokinase and hexokinase. Based on this information, which of the following is a true statement? .....answer.....Glucokinase has a higher Km than hexokinase.
A new enzyme is discovered that increases in activity when it is phosphorylated on an exposed tyrosine. Phosphorylation of this amino acid is classified as which of the following?
a) feedback inhibition
b) transcriptional activation
c) covalent modification
d) increased protein ubiquitination .....answer.....covalent modification
All of the following are considered coenzymes except: .....answer.....Heme
Heme is not considered a coenzyme. It is a prosthetic group within hemoglobin that binds iron. The heme ring itself is not part of oxygen binding.
Cleavage of fructose 1, 6 bisphosphate to dihydroxyacetone and glyceraldehyde 3-phosphate is achieved by what class of enzymes: .....answer.....Lyase
If a mutation is made within the active site of an enzyme resulting in a decrease in Km, which of the following will be true with respect to the enzyme kinetics? .....answer.....The enzyme will require a lower substrate concentration to reach ½Vmax
The following represents a series of reactions. As levels of B increase, this will decrease the conversion of S3 to B. Which of the following best describes this type of regulation in a biosynthetic pathway? .....answer.....Feedback inhibition
Which of the following is an example of enzyme regulation through covalent modification?
a) binding of GTP to a monomeric G-protein
b) phosphorylation of muscle glycogen
c) digestion of misfolded proteins by lysosomes
d) cleavage of chymotrypsinogen to chymotrypsin .....answer.....phosphorylation of muscle glycogen phosphorylase
c) allosteric inhibition
d) allosteric activation .....answer.....allosteric activation
An enzyme is participating in a general acid-base catalysis reaction with an optional reaction pH of 6.0. If acid is added to the environment reducing the pH to 3, what is the likely impact to the rate of reaction? .....answer.....The rate of the reaction is likely to decrease as the pH is out of optimal catalytic range
The following represents a series of reactions. As levels of B increase, this will decrease the conversion of S3 to B. Which of the following best describes this type of regulation in a biosynthetic pathway?
a) feedback inhibition
b) feedforward activation
c) covalent regulation
d) inducible regulation .....answer.....feedback inhibition
Use the figure below to compare the activities of glucokinase and hexokinase. Based on this information, which of the following is a true statement? .....answer.....Glucokinase has a higher Km than hexokinase.
Enzymes reduce the activation energy for a reaction. All enzymes do this by: .....answer.....Enzymes help to reduce the activation energy of a reaction by stabilizing high energy intermediates. By have a flexible active site that is highly complementary to the transition state of a substrate this is most readily achieved.
An allosteric activator will increase enzyme activity through which of the following mechanisms? .....answer.....Binding the enzyme, and keeping it in the "R" conformation
Which of the following best describes an enzyme inhibitor that increases the Km but does not change the Vmax? .....answer.....A competitive inhibitor
Heat can be generated in the brown adipose tissue of hibernating mammals. Which of the following is the most likely mechanism by which this occurs? .....answer.....Expression of a protein that uncouples the ETC
The association of DNA and histones can be modified by histone acetylation. A decrease in histone acetylation will have which of the following impacts on the assocation of DNA and histones?
