Biochemistry test 1 Cutouts
Maple syrup disease is caused by a deficiency in which of the following enzymes? A. Branched chain alpha ketoacid dehydrogenase B. Bistidase C. Cystatbionase D. Homogentisate oxidase E. Propionyl CoA carboxylase
A. Branched chain alpha ketoacid dehydrogenase
Which of the following enzymes is responsible for oxidative deamination? A. Glutamate dehydrogenase B. Alanine aminotransferase C. Carbamoyl phosphate synthetase I D. D amino acid oxidase E. Aspartate aminotransferase
A. Glutamate dehydrogenase
An amino acid with nonpolar side chain is : A. Methionine B. Aspartate C. Arginine D. Glutamine E. Threonine
A. Methionine
A block in the synthesis of melanin causes albinism. Which amino acid is melanin derived from? A. Tyrosine B. Threonine C. Histidine D. Valine E. Glutamate
A. Tyrosine
A block in the synthesis of phenylalanine causes phenylketouria . Which amino acid becomes essential in PKU patients? A. Tyrosine B. Threonine C. Histidine D. Valine E. Glutamate
A. Tyrosine
A chronic smoker, who has smoked for 40 years, comes to your office with complaints of breathing difficulties. You notice that his breathing is shallow and labored. A chest xray shows no evidence of lung cancer. You diagnose the patient with chronic emphysema. Which of the following molecules is likely to be deficient in this patient and cause this condition? A. Vitamin C B. Alpha-1 antitrypsin C. Elastase D. Copper E. Pyridoxal phosphate
B. Alpha-1 antitrypsin
What amount of chemical energy expended by a resting individual is used to maintain ion gradients? A. One half B. One quarter C. One third D. Three quarters E. All of it
B. One quarter
A weak acid has a pKa of 5. What is the pH of a solution containing this acid when the salt (conjugate base A-) concentration is 1000 times greater than the indissociated acid (HA) A. 3 B. 5 C. 8 D. 10 E. 12
C. 8
Which of the following would NOT cause hyperphenylalaninenija? A. A block in the synthesis of tyrosine B. Dihydrobiopterin synthase deficiency C. Dihydrobiopterin reductase deficiency D. Phenylalanine Hydroxylase deficiency E. Tyrosine Hydroxylase deficiency
C. Dihydrobiopterin reductase deficiency
The rate limiting step of prophyrin biosynthesis is inhibited by which of the following compounds: A. Heme B. Lead C. Hemin D. Uroporphyrinogen E. Iron
C. Hemin
Which of the following is FALSE regarding a noncompetitive inhibitor of enzyme activity? A. It binds allosterically to the enzymes B. It lowers the Vmax of the reaction C. It must closely resemble the structure of the substrate to be an effective inhibitor D. It does not change the Km of the enzyme for the substrate E. It cannot be overcome by adding more substrate
C. It must closely resemble the structure of the substrate to be an effective inhibitor
The class of enzyme that catalyzes formation of bonds between carbon and O, S, and N, coupled to the hydrolysis of a high energy phosphate bond is: A. Oxidoreductase B. Isomerase C. Ligase D. Lyase E. Hydrolase
C. Ligase
Molecules which bind to a hormone or neurotransmitter which ultimately results in a specific intracellular response are named: A. Protein kinase B. Second messengers C. Receptors D. Enzymes E. G-proteins
C. Receptors
A domain is an example of: A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure E. Quintenary structure
C. Tertiary structure
Which of the following is NOT characteristic of catabolic reactions? A. They serve to generate energy B. The often produce NADPH or FADH2 C. They are divergent processes in which a few precursors form a wide variety of polymeric products D. They often involve hydrolysis of macromolecules E. Glycolysis is an example of a catabolic pathway
C. They are divergent processes in which a few precursors form a wide variety of polymeric products
"Y" is the single letter code for which amino acid? A. Phenylalanine B. Tryptophan C. Tyrosine D. Glycine E. Valine
C. Tyrosine
The bohr effect on hemoglobin A results in: A. An increased oxygen release at higher pH B. An increased affinity of HbA for oxygen at a higher partial pressure of CO2 C. An unloading of oxygen from hemoglobin in the lungs D. A right shift in the oxygen dissociation curve E. A sleep Hb because it is bored of biochemistry
D. A right shift in the oxygen dissociation curve
Jaundice is caused by a buildup of which of the following compounds? A. Biliverdin B. Bilirubin biglucuronide C. Urobilin D. Bilirubin E. Stercobilin
D. Bilirubin
Of the molecules molecules listed below, which one can easily diffuse across the plasma membrane of the cell? A. Glucose B. Amino acids C. ATP D. Carbon dioxide E. Calcium
D. Carbon dioxide
The hypothesis which explains how the free energy generated by the transport of electrons by the electron transport chain is used to produce ATP from ADP + Pi is called: A. Osmosis hypothesis B. Mitoses hypothesis C. Common knowledge hypothesis D. Chemiosmotic hypothesis E. Oligomycin hypothesis
D. Chemiosmotic hypothesis
Hemoglobin A : A. Contains a single polypeptide chain B. Contains one heme molecule per HbA molecule C. Contains over 80% of its structure as beta-pleated sheets D. Contains 2 alpha chains and 2 beta chains E. Exhibits a hyperbolic oxygen binding curve
D. Contains 2 alpha chains and 2 beta chains
Which of the following is an example of teritary structure in a protein? A. Primary amino acid sequence B. Alpha helix C. Beta sheet D. Domain E. Dimer of 2 protein subunits
D. Domain
Which of the following diseases results from the defective synthesis of collagen? A. Christmas disease B. Emphysema C. Hyaline membrane disease D. Ehlers-Danlo syndrome E. Von Willebrand disease
D. Ehlers-Danlo syndrome
______ is a component of the extrinsic pathway in blood clotting A. Hageman Factor B. Antihemophilic factor C. Factor V D. Factor VII E. Factor IX
D. Factor VII
Which is true about porphyrins? A. Porphyrins are formed by the linkage of 16 pyrrole rings B. Type IX porphyrins are the most common form in humans C. Squalene is a building block of porphyrins D. Ferrochelatase helps Fe2+ incorporate into heme E. The endpoint in the porphyrin biosynthetic pathway is porphobilinogen
D. Ferrochelatase helps Fe2+ incorporate into heme
A 10 year old, African American boy presents to your office in Denver, CO with severe pain in his lower back, legs and abdomen. He just finished hiking up a small mountain with his class. His peripheral blood hemoglobin is 7.8% (normal = 12-16%) and his hemotocrit is 23.4% (normal = 41-53%). Microscopy of his blood shows many crescent shaped red blood cells. The following mutation caused this condition: A. Glu 6 to Lys 6 in the beta chain of hemoglobin B. Lys 6 to Glu 6 in the beta chain of hemoglobin C. Val 6 to Glu 6 in the beta chain of hemoglobin D. Glu 6 to Val 6 in the beta chain of hemoglobin E. Glu 6 to Val 6 in the alpha chain of hemoglobin
D. Glu 6 to Val 6 in the beta chain of hemoglobin (Hemoglobin S disease)
Compound that is essential for the detoxification of bilirubin, steroids and drugs A. Acetic acid B. Oxaloacetic acid C. Stearic acid D. Glucuronic acid E. Pyruvic acid
D. Glucuronic acid
Regarding the tertiary structure of protein: A. A domain is a linear, extended stretch of amino acid sequence B. Two methionines condense to form a disulfide bond C. Hydrophobic amino acids generally interact and are found on the surface of the protein D. Hydrophobic interactions, hydrogen bonds and ionic interactions all can contribute to stabilizing tertiary structure E. It requires that individual polypeptide chains interact to form a multi-subunit complex
D. Hydrophobic interactions, hydrogen bonds and ionic interactions all can contribute to stabilizing tertiary structure
Which of the following is FALSE regarding the pKa of a titratable group of amino acid? A. When the pH of the solution equals the pKa, the buffering capacity of the group is maximal B. When the pH of the solution equals the pKa, one half of the carboxyl groups will be protonated and one half will be deprotonated C. When the pH is 2 pH units below the pKa of an amino group, the amino group will be positively charged D. It equals the [H+] multiplied by the [A-] divided by the [HA] E. The pKa does not apply to amino and carboxyl groups of the amino acid side chains
D. It equals the [H+] multiplied by the [A-] divided by the [HA]
A patient presents in the ER 2 days after experiencing chest pains. A myocardial infarction is diagnosed. Which of the following enzyme activities would be elevated at the time of admission? A. CK1 (Creatine kinase 1) B. CK2 (Creatine kinase 2) C. CK3 (Creatine kinase 3) D. LDH (Lactate dehydrogenase) E. ALT (Alanine aminotransferase)
D. LDH (Lactate dehydrogenase)
Which of the following is NOT true about porphyrins? A. Porphyrins are formed by the linkage of 4 pyrrole rings B. Type 3 porphyrins are the most common form in humans C. ALA is a building block of porphyrins D. Uroporphyrinogen is a yellow pigment E. The endpoint in the porphyrin biosynthetic pathway is heme
D. Uroporphyrinogen is a yellow pigment
Which of the following is the first catecholamine synthesized in the catecholemine biosynthetic pathway? A. epinephrine B. dopamine C. norepinephrine D. tyrosine E. melanin
Dopamine
Which of the following amino acids does not have optical isomers around the alpha carbon atom? A. Alanine B. Lysine C. Histidine D. Proline E. Glycine
E. Glycine
Which of the following is NOT TRUE when one determines the amino acid composition of proteins after the complete acid hydrolysis of the protein? A. The protein that is hydrolyzed must be pure B. Ninhydrin is used to produce a purple derivative of the amino acid C. N, Q, and W must be determined using a different chemical method D. The absolute number of each amino acid in the protein can only be determined i the molecular weight of the protein is known E. This procedure directly gives the sequence of the amino acids in the protein
E. This procedure gives the sequence of the amino acids in the protein
_____ is a short acting anticoagulant used to prevent blood clotting when blood is drawn into a vacutainer tube A. Coumarin B. Urokinase C. Heparin D. tPA (Tissue plasminogen activator) E. Streptokinase
Heparin
Among patients exhibiting defects of glycolytic enzymes about 95% show a deficiency is which specific enzyme?
Pyruvate kinase
All of the following are classified as amino acids with nonpolar side chains excepts: A. Threonine B. Methionine C. Leucine D. Valine E. Tryptophan
A Threonine
_____ is a nonpolar amino acid while _____ is a basic amino acid A. Alanine, arginine B. Lysine, leucine C. Valine, Aspartate D. Serine histidine E. Asparagine, tyrosine
A. Alanine arginine
In cyanide poisoning: A. Amyl nitrate is given to the patient to cause the formation of methemoglobin B. The binding of cyanide promotes the formation of the R form of hemoglobin C. The patient is treated to cause the cyanide to bind to myoglobin D. The binding of cyanide to hemoglobin is called the Bohr effect E. Cytochrome electron transport is not affected
A. Amyl nitrate is given to the patient to cause the formation of methemoglobin
A patient calls to complain about a headache. After eliminating any serious disorder, you say "Take two aspirin and call me in the morning". Aspirin is an irreversible enzyme inhibitor, therefore: A. Aspirin forms a covalent bond with the enzyme B. Eventually enzyme activity will return when the aspirin dissociates from the enzyme C. Enzyme activity will return even if there is no new protein synthesis D. Once aspirin inhibits the enzyme, the inhibition can be relieved by adding an analogue of aspirin E. There is no effect of aspirin on the Km or Vmax
A. Aspirin forms a covalent bond with the enzyme
Cystic fibrosis is caused by a genetic mutation in the complex membrane protein cystic fibrosis transmembrane conductance regulator that results in a defect in the efflux of which ion across the respiratory epithelial membrane? A. Chloride B. Calcium C. Bicarbonate D. Hydrogen E. Magnesium
A. Chloride
Which of the following is the rate limiting enzyme of porphyrin? A. Delta-aminolevulinate synthase B. Ferrochelatase C. HMG COA reductase D. Uroporphyrinogen I synthase E. Pyruvate kinase
A. Delta-aminolevulinate synthase
Which of the following is FALSE regarding the structure of collagen? A. It's secondary structure consists almost totally of alpha-helix B. 3 alpha chains intertwine to form a triple helix C. It is very elongated and fiber-like D. It contains hydroxyproline and hydroxylysine residues E. It consists of the triplet amino acid repeat, G-X-Y, repeated about 333 times
A. It's secondary structure consists almost totally of alpha-helix
An enzyme which adds a phosphate group to a protein is named a: A. Kinase B. Phosphatase C. Isomerase D. Mutase E. Aldolase
A. Kinase
Which of the following is FALSE regarding hemoglobin A? A. Methemogloblin binds oxygen very tightly B. In the taut form "t", HbA has a low affinity for oxygen C. In the relaxed form "r", HbA has a high affinity for oxygen D. The fourth oxygen binds much easier to HbA than the first oxygen E. A sigmoidal oxygen binding curve is obtained when plotting the % saturation with oxygen versus the partial pressure of oxygen
A. Methemogloblin binds oxygen very tightly
The terminal cytochrome in the electron transport chain contributes electrons to which molecule? A. Molecular oxygen B. Molecular hydrogen C. Water D. ATP E. AMP
A. Molecular oxygen
Which of the following is FALSE regarding the sequencing of proteins using Edman degradation? A. Sequencing occurs in the carboxyl to amino terminals direction B. The independent sequencing of purified, overlapping peptides is required for proteins containing 200 amino acids C. An automated protein sequencing machine is normally used D. CNBr can be used to cleave the protein on the carboxyl side of methionine residues E. Trypsin can be used to cleave the protein on the carboxyl side of Lys and Arg residues
A. Sequencing occurs in the carboxyl to amino terminal direction
Which of the following is FALSE regarding the alpha helix structure of a protein? A. The side chains point inward into the helix B. The hydrogen bonds are parallel to the axis of the helix C. There is 3.6 amino acids per turn of the helix D. It is a right-handed helix E. It is a type of secondary protein structure
A. Side chains point inward into the helix
Choose the correct order below for the synthesis of collagen: A. Synthesis of pro-alpha chains, formation of procollagen, secretion, proteolysis to collagen, crosslinking B. Synthesis of pro-alpha chains, formation of procollagen, crosslinking, secretion, proteolysis to collagen C. Formation of procollagen, synthesis of pro-alpha chains, secretion, proteolysis to collagen, crosslinking D. Formation of procollagen, crosslinking, synthesis of pro-alpha chains, proteolysis to collagen, secretion E. Synthesis of pro-alpha chains, proteolysis to collagen, formation of procollagen, secretion, crosslinking
A. Synthesis of pro-alpha chains, formation of procollagen, secretion, proteolysis to collagen, crosslinking
Which of the following is FALSE about the structure of collagen? A. The individual polypeptide chains form long stretches of alpha helix B. 3 alpha chains intertwine to form a triple helix C. Each polypeptide chain is about 1000 amino acids long D. Hydroxylysine and hydroxyproline residues are common E. A deficiency of ascorbic acid results in weaker collagen bundles
A. The individual polypeptide chains form long stretches of alpha helix
The turnover number of an enzyme is: A. The number of substrate molecules converted to product per enzyme B. The concentration of substrate at which the initial rate of the reaction is one half of the maximal velocity of the reaction C. The same as the maximal velocity of a reaction D. Decreases in free energy of a reaction caused by enzymes E. Dependent on the concentration of the enzyme in the reaction
A. The number of substrate molecules converted to product per enzyme
In the Anfinsen experiment, ribonuclease was treated with a slow reducing agent and urea to completely denature it. It was then slowly renatured by dialysis of the urea out of the solution and oxidation, resulting in the reconstitution of a functional enzyme. This experiment proved that: A. The primary sequence of a protein determines its 3D structure B. Only proteins with quaternary structure have enzymatic activity C. Peptide bonds are broken by urea D. Chaperonins are always required for correct protein folding E. Only alpha helices can refold after denaturation
A. The primary sequence of a protein determines its 3D structure
Calculate the isoelectric point of aspartic acid is the pKa of the alpha amino group is 10, the pKa of the alpha carboxyl group is 2 and the pKa of the side chain carboxyl group is 4 A. 2 B. 3 C. 4 D. 6 E. 7
B. 3
The pKa for the alpha carboxyl group of glutamic acid is 2.1, the pKa a for the side chain carboxyl is 4.3 and the pKa for the alpha amino group is 9.7. What is the isoelectric point of glutamic acid? A. 2.1 B. 3.2 C. 4.3 D. 7.0 E. 9.7
B. 3.2
The pKa of a weak acid is 8.4. In a solution, the concentration of the conjugate base is 1mM and the concentration of the protonated acid is 100mM. The pH of the solution is: A. 5.4 B. 6.4 C. 7.4 D. 8.4 E. 10.4
B. 6.4
Which of the following is NOT a feature of collagen? A. Repeating Gly-X-Y amino acid sequence, where X is often proline and Y is frequently hydroxyproline or hydroxylysine B. Allysine residues C. Triple helix structure D. Glycosylated lysines and hydroxylysine E. Interchain crosslinks
B. Allysine residues
What is the name of the coupled biochemical transport process which transports two molecules across a cellular membrane in opposite directions? A. Symport B. Antiport C. Biport D. Uniport E. Airport
B. Antiport
Cardiac glycosides are extremely useful for congestive heart failure because they increase the strength and force of contraction of the heart muscle by inhibiting the sodium pump which results in an increase in which ion in the cardiomyocytes? A. Chloride B. Calcium C. Bicarbonate D. Hydrogen E. Magnesium
B. Calcium
Treatment of a patient with _____ will inhibit the synthesis of leukotrienes, prostaglandins, and thromboxanes, while treatment with _____ causes an irreversible inhibition of the enzyme required for the synthesis of only thromboxanes and prostaglandins A. Aspirin, Cortisol B. Cortisol, Aspirin C. Cortisol, Indomethacin D. Cortisol, Phenylbutazone E. Indomethacin, Aspirin
B. Cortisol, Aspirin
The term given to the measurement of randomness is bioenergetics is: A. Enthalpy B. Entropy C. Free energy D. Frenzy E. Equilibrium
B. Entropy
Which of the following is used in determining the amino acid sequence of a protein that is 400 amino acids long via Edman degradation? A. Complete hydrolysis of the entire protein into the individual amino acids B. Generation of protein fragments by treatment with proteases and cyanogen bromide C. Ninhydrin D. An anion exchange column to separate the mixtures of amino acids E. Sequential removal of the amino acids from the carboxyl terminus of the protein
B. Generation of protein fragments by treatment with proteases and cyanogen bromide
Transamination of all but a few amino acids transfers amino groups to which of the following amino acids? A. Glutamine B. Glutamic acid C. Aspartate D. Glycine E. Ornithine
B. Glutamic acid
Which of the following amino acids does not have a chiral carbon? A. Cysteine B. Glycine C. Histidine D. Arginine E. Aspartic acid
B. Glycine
When electron transport is uncoupled from oxidative phosphorylation energy is given off in the form of: A. Light B. Heat C. Water D. Steam E. Oxygen
B. Heat
Which of the following is FALSE regarding elastin? A. It contains desmosine B. It is abnormal in Ehlers-Danlos Syndrome C. Alpha1-antitrypsin prevents its degradation D. Its level is decreased in the lungs of patients with emphysema E. It forms a 3D web like network
B. It is abnormal in Ehlers-Danlos Syndrome
An enzyme that catalyzes the cleavage of C-C, C-S, and C-N bonds fall into the class of enzymes named: A. Isomerases B. Ligases C. Lyases D. Tranferases E. Hydrolases
B. Lyases
The catabolism of the branched chain amino acids takes place primarily in what? A. Liver B. Muscle C. Spleen D. Kidney E. Brain
B. Muscle
Which of the following would be the consequences if a patient had both alkaptonurea and steatorrhea? A. Bright yellow urine, feces float B. Orange urine, feces sinks C. Black urine, Feces floats D. Pale gray urine, feces sinks E. Green urine, feces floats
B. Orange urine, feces sinks
Which of the following statement is true? A. The maximum buffering capacity of a weak acid occurs when the pH is 2 pH units or greater away from the pKa B. The pH changes least when a strong acid or base is added to the solution containing a weak acid in which the pH of the solution is equal to the pKa of the weak acid C. An amino acid in its zwitterion form has a +1 net charge D. The larger the Ka of an acid is, the weaker the acid is E. Glycine exists as 2 stereoisomers and L form and D form
B. The pH changes least when a strong acid or base is added to the solution containing a weak acid in which the pH of the solution is equal to the pKa of the weak acid
Uncoupling of oxidative phosphorylation implies that: A. Cellular metabolism ceases B. ATP formation continues but electron transport ceases C. ATP formation ceases but electron transport continues D. NADPH dehydrogenase activity of the mitochondrion is inhibited E. Mitochondrion ceases to utilize NADPH
C. ATP formation ceases but electron transport continues
Hemoglobin A (HbA): A. Contains a single polypeptide chain B. Cannot bind 2,3-BPG C. Binds oxygen in a cooperative fashion D. Normally binds ferric iron E. Exists in a taut "t" form that has a high oxygen binding affinity and a relaxed "r" form which has a low affinity for oxygen
C. Binds oxygen in a cooperative fashion
Which of the following is TRUE of alpha helix? A. Side chains of the amino acids point inward B. The intrachain hydrogen bonds are perpendicular to the axis of the helix C. Each turn of the helix contains 3.6 amino acids D. A proline residue favors the formation of the alpha helix E. It can be parallel or antiparallel
C. Each turn of the helix contains 3.6 amino acids
There is a high incidence of an abnormal hemoglobin beta chain in african americans. Which of the following statements is TRUE? A. There is a mutation of valine to glutamic acid at position 6 in the beta chain B. HbS, which has 2 abnormal beta chains, migrates more rapidly toward the positive pole in an electrical field C. Individuals who have "sickle cell trait" are more resistant to malaria than those that have 2 normal copies of the beta chain D. Patients with 2 abnormal beta chains show no clinical symptoms of disease E. HbS is more soluble in the deoxygenated form than HbA
C. Individuals who have "sickle cell trait" are more resistant to malaria than those that have 2 normal copies of the beta chain
The largest amount of serotonin in the body is found in which tissue? A. Brain B. Spinal cord C. Intestinal mucosa D. Muscle E. Liver
C. Intestinal mucosa
Which of the following is NOT true regarding elastin? A. It contains allysine residues B. It can contain desmoine crosslinks C. It's degradation is stimulated by alpha1-antitrypsin D. Cigarette smoking can promote emphysema due to increased elastase activity in the lungs E. It can stretch several times its relaxed length
C. It's degradation is stimulated by alpha1-antitrypsin
In determining the amino acid sequence of a protein: A. An amino acid analyzer can give the sequence directly B. An amino acid sequencer determines the sequence starting at the carboxyl terminus of the protein C. Overlapping peptide fragments must be generated and sequenced individually for a protein having 300 amino acids D. Edman degradation cannot be used E. The sequence of a dimer containing 2 different subunits can be obtained without purifying the subunits away from each other
C. Overlapping peptide fragments must be generated and sequenced individually for a protein having 300 amino acids
Which of the following statement is TRUE? A. Amyl nitrate is used to treat carbon monoxide poisoning because it promotes the formation of oxyhemoglobin B. Alpha thalassemias are more common than beta thalassemias because there are two adult alpha chain genes and 4 adult beta genes chain genes C. Sickle cell anemia has no effect in fetal development because the gamma hemoglobin chain is expressed during this time to form fetal hemoglobin, HbF D. Hemoglobin C disease results from 2 different beta chain mutations, one of which is the same as occurs in sickle cell disease E. In hemoglobin H disease, all 4 hemoglobin beta chains are either defective or absent
C. Sickle cell anemia has no effect in fetal development because the gamma hemoglobin chain is expressed during this time to form fetal hemoglobin, HbF
Which of the following is FALSE regarding dietary protein and the amino acids that are released upon its digestion? A. Carbohydrates can be derived from the carbon skeletons of amino acids B. The main dietary requirement of protein is as a source of the essential amino acids C. The biologic value of all vegetables is 67% D. A new burn patient in a trauma units has a negative nitrogen balance E. A diet that contains carbohydrates is protein sparing
C. The biologic vale of all vegetables is 67%
Which of the following is NOT true of enzymes? A. The active site is a cleft into which the substrate fits B. A holoenzyme is the form that contains both the enzyme protein and a necessary cofactor C. The turnover number is defined as the number of substrate molecules converted to product per unit time (millimole product formed/minute) D. Some enzymes are present in separate subcellular compartments to facilitate the occurrence of an overall metabolite pathway E. Some enzymes can accelerate the rate of a reaction one million times faster than would occur in the spontaneous, uncatalyzed reaction
C. The turnover number is defined as the number of substrate molecules converted to product per unit time (millimole product formed/minute)
In hemoglobin C disease: A. A deficiency in the beta chain causes embryonic death B. There is an imbalance in either alpha or beta chain synthesis C. Sickling of the red blood cells occurs at high altitudes D. A mild, chronic hemolytic anemia occurs E. The defective hemoglobbin migrates to the same position upon polyacrylamide gel electrophoresis as hemoglobin S and hemoglobin A
D. A mild, chronic hemolytic anemia occurs
A peptide bond: A. Has single bond characteristics B. Usually exists in a cis configuration C. Is charged D. Is planar E. Allows for free rotation of the carbonyl carbon and amide nitrogen atoms around it
D. Is planar
Second messengers are necessary because: A. Steroid hormones are lipid soluble B. mRNA has a short half-life C. First messenger is DNA D. Peptide hormones generally do not cross cell membranes E. Hormones are intracellular
D. Peptide hormones generally do not cross cell membranes
The most common covalent modification of an enzyme protein that regulates its activity is A. Methylation B. Glycosylation C. Attachment of a fatty acid D. Phosphorylation E. Crosslinking of enzyme subunits in desmoine linkages
D. Phosphorylation
Which of the following is NOT a characteristic of a peptide bond? A. Always in trans configuration B. Partial double bond character C. Rigid D. Positive charge E. Planar
D. Positive charge
Which of the following requires multiple protein subunits? A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure E. All of the above
D. Quaternary structure
Which of the following is FALSE regarding a protein enzyme? A. Catalyst and is not consumed by the reaction B. Contains an active site in which the amino acids lining the site form a complementary surface to that of the substrate C. Lowers free energy of activation for a chemical reaction D. Increases the probability that the substrate will be converted to the transition state form E. Alters the final equilibrium of a chemical reaction
E. Alters the final equilibrium of a chemical reaction
A 62 year old white male who is noticeably obese, comes to the emergency room. The day before he had a 2 minute episode of severe chest pains that occurred when mowing the lawn in 95 degree New Orleans heat. You suspect that he had a myocardial infarction. Which enzyme level would be most likely to be elevated in his serum? A. ALT (Alanine aminotransferase) B. GPT (Glutamate-pyruvate transaminase) C. Alkaline phosphatase D. CK1 (Creatine kinase 1) E. CK2 (Creatine kinase 2)
E. CK2 (Creatine kinase 2)
A 2 year old presents with bleeding that is steady from a cut on his hand for 15 minutes. You suspect that he suffers from hemophilia a. Which clotting factor would be missing if you diagnosis were correct? A. Factor V B. Factor X C. Von Willebrand factor D. Factor IX E. Factor VIII
E. Factor VIII
A patient presents with hemolytic anemia. Genetic analysis shows that she has one normal alpha globin chain but that the other 3 copies have been completely deleted from her genome. This patient has : A. Sickle cell anemia B. Beta-thalassemia minor C. Beta-thalassemia major D. Hydrops fetalis E. Hemoglobin H disease
E. Hemoglobin H disease
Myoglobin : A. Contains two alpha chains and two beta chains B. Binds oxygen in a cooperative fashion C. Binds 2,3-BPG as an allosteric modulator D. Usually contains iron in the ferric form E. Is composed largely of alpha helical structures
E. Is composed largely of alpha helical structures
Which of the following inactive digestive enzymes is NOT activated by trypsin? A. Procarboxypeptidase A B. Trypsinogen C. Chymotrypsin D. Proelastase E. Pepsinogen
E. Pepsinogen
The enzyme that catalyzes the catabolic hydrolysis of cyclic AMP is: A. Adenylate cyclase B. Protein kinase C. Phosphorylase D. Phosphatase E. Phosphodiesterase
E. Phosphodiesterase
Which of the following clinical treatments would be improper and jeopardize patient health A. Administering tissue plasminogen activator (tPA) to a patient to dissolve a thrombus B. Administering urokinase to a patient to dissolve a thrombus C. Administering tissue streptokinase to a patient to dissolve a thrombus D. Administering recombinant Factor 8 to a patient suffering for Hemophilia a E. Prescribing coumadin to a patient suffering from Von Willebran disease
E. Prescribing coumadin to a patient suffering from Von Willebran disease
All of the following are examples of secondary structures in proteins, EXCEPT: A. Alpha helix B. Beta turn C. Beta bend D. Beta pleated sheet E. Primary amino acid sequence
E. Primary amino acid sequence
Which of the following causes vasoconstriction, decreases the synthesis of cAMP and is produced primarily in platelet? A. LTB4 (Leukotriene B4) B. Prostacyclin C. PGF20 (Prostaglandin F20) D. PGE2 (Prostaglandin E2) E. TXA2 (Thromboxane A2)
E. TXA2 (Thromboxane A2)
In the synthesis of collagen, : A. Hydroxylation of lysines occurs only after 3 alpha chains assemble to form a triple helix B. Lysines and prolines are hydroxylated by the same enzyme C. Lysyl ocidase crosslinking occurs inside of the cell D. Cleavage of the N terminal and C terminal regions of procollagen occurs prior to formation of the collagen triple helix E. The hydrophobic signal sequences is needed for the eventual secretion of procollagen into the extracellular matrix
E. The hydrophobic signal sequences is needed for the eventual secretion of procollagen into the extracellular matrix
Which of the following is TRUE of the bioenergetics of enzymatic reactions? A. The reactions are all thermodynamically and physiologically irreversible B. The enzyme provides an alternative reaction pathway that has a higher free energy of activation C. At equilibrium, all of the enzyme molecules are in ES complex D. At equilibrium, all of the substrate and product molecules are in the transition state E. The rate of the reaction is increased by enzymes because they stabilize the substrate molecule into a form resembling the transition state
E. The rate of the reaction is increased by enzymes because they stabilize the substrate molecule into a form resembling the transition state
Which of the following is NOT TRUE regarding the binding of oxygen to hemoglobin? A. It binds the fourth molecule of oxygen with a 300 fold affinity than the first oxygen molecule B. Carbon monoxide binds to hemoglobin with a 220 fold higher affinity than oxygen C. It displays cooperative binding D. Low pH promotes the dissociation of oxygen from hemoglobin E. The taut "t" form of hemoglobin has a higher affinity for oxygen than the relaxed "r" state
E. The taut "t" form of hemoglobin has a higher affinity for oxygen than the relaxed "r" state
Which of the following is FALSE regarding enzymes? A. An enzyme that follows Michaelis-Menten kinetics shows a hyperbolic increase in initial velocity with an increased concentration of substrate. B. When one is measuring that initial velocity of an enzyme-catalyzed reaction, the rate constant, k-2, (E+P-> ES) is very small and can be ignored C. The Km reflects but is not the same as the binding affinity for the substrate that an enzyme for the substrate D. An enzyme with a high Km has a lower affinity for the substrate than an enzyme with a low Km for the substrate E. When the reaction is proceeding at maximum velocity, the reaction rate is first order with respect to the substrate concentration
E. When the reaction is proceeding at maximum velocity, the reaction rate is first order with respect to the substrate concentration
Membrane bound phosphotidylinositol 1,4,5-triphosphate is hydrolyzed to inositol 1.4.5-triphosphate and diacylglycerol by which hydrolase? A. Phospholipase A B. Phospholipase B C. Phospholipase C D. Phospholipase D E. Phospholipase E
Phospholipase C