bcmb tests

Test 1 12/6/12 11:46 PM

Question 1 • The two most important buffer systems in blood are:

o Hemoglobin and bicarbonate Question 2

• The pH of blood changes from normal to 7.25. As a result, the patient will: o Increase pH by breathing more slowly and Bicarb concentration should

DROP Question 3

• Di Beatty is a patient who has had IDDM for seven years. She missed her scheduled insulin shot and ate a candy bar. She was brought to the clinic after developing ketoacidosis.. Compared to normal, you would expect:

o Low PaCO2 and lower serum bicarbonate Question 4

• An acid anhydride is formed by removing water from o Carboxylic acid and amino group?

Question 5

• The R-groups of the amino acids valine, leucine, and isoleucine are all: o Nonpolar and branched chain

Question 6

• The pKa's for this amino acid are 2, 9, and 10.5. At a pH of 7.4, this amino acid has a net positive charge. The amino acid is:

o Lysine Question 7

• At pH of 7, a salt bond would most likely form between the R-groups of: aspartate and arginine

Question 8

• Treatment for cystinurea could include: o Reduction of methionine in diet, since this is a precursor to the synthesis of

cysteine

Question 9

• In this type of structure, most of carbonyl groups of peptide bonds forms a hydrogen bond with the amide nitrogen of another peptide bond four amino acids further down the polypeptide chain.:

o Alpha-helix Question 10

• Concerning prion disease, the amyloid protein in the brain is thought to result from o The lowering of the activation energy for the conversion of PrPc to PrPSC

Question 11

• Which of the following terms describes hemoglobin but not myoglobin? o The protein contains alpha and beta chains

Question 12

• Concerning Di Abietes, HbA1c o Measure compliance over the last six weeks to eight weeks

Question 13

• The alpha helix found in myoglobin can best be described as o Secondary structure

Question 14

• Will Sichel has sickel cell anemia. His beta-chains are changed by the substitution of: o A nonpolar valine for a charged glutamate

Question 15

• You have an aqueous solution on your lab bench. The concentration of hydroxide ions is 5 x 10-7. You can determine:

o That the proton concentration is 2 x 10-8 Question 16

• Phosphate buffer in blood has a pKa = 6.8. If the pH of blood was 7.1, and the concentration of HPO4 was 0.8 mmol/L , What would be the concentration of H2PO4?

o 0.4 mmol/L

Question 17

• Which of the following statements about buffers are TRUE? o Buffers work best when the pH of the solution is within 1 pH unit of its pKa

Question 18

• You are working with arterial blood. The patient is acidotic with a pH = 7.1. The pKa for carbonic acid is 6.1. The partial pressure of CO2 is 37 mm Hg. The concentration of CO2is 1.1 mM. What is the concentration of bicarbonate ion?

o 11 mM Question 19

• Which of the following statements regarding monosaccharides is FALSE? o Gluconate and glucuronate are both formed by the REDUCTION of glucose

Formed by OXIDATION Question 20

• An amide bond is formed from a o Carboxyl group and an amino group

Question 21

• At physiologic pH, which R-groups of the following pairs could successfully form a salt bond?

o Glu-Arg Question 22

• Which of the following amino acids has an isoelectric point of about 11 o Arginine

Question 23

• All of the following are treatments for cystinuria: o Increase fluid intake o Reduce methioine in diet o Sonic fracturing of cystine stones o Drugs which convert cystine to more soluble compounds

Question 24 • Which R-group of the following is MOST likely to form hydrogen bonds in

aqueous solution? o Serine?

Question 25

• One of the following is NOT usually a force that helps to hold the monomer units of a quaternary protein together?

o Peptide bonds Question 26

• Of the following states of hemoglobin (Hb), which is least likely to bind the next molecule of oxygen (02)?

o Hb Question 27

• Assume that an acid and the salt of an acid are equally soluble at pH 7.7 and that the pKa for the conversion of the salt to the acid is 5.7. As you add either the salt of the acid or the acid to a solution buffered at 7.7, which would precipitate first?

o Salt of the acid Question 28

• Which of the following statements regarding ligand binding are correct? o Some proteins require ligands in order to perform their function o Enzymes with their attached ligands are called holoenzymes o The heme group on hemoglobin is an example of a tightly bound ligand o Some apoproteins will bind to ligands

Question 29

• Concerning a patient with diabetic ketoacidosis, which compound in her blood reacts with nitroprusside?

o Acetoacetate Question 30

• Which of the following is a free radical? o O2

-

Question 31

• Regarding any untreated person having diabetes, what level of fasting blood sugar would you expect?

o 126 mg/dL Question 32

• If a person breathes into a paper bag, you would expect their blood CO2 to o Increase and their blood pH to decrease?

Question 33

• A thioester is formed by removing water from o A sulfhydryl group and a carboxylic acid

Question 34

• Refer to the structures in Figure 1. Which column contains the structure for a ketohexose?

o Column D

Question 35

• Refer to the structures in Figure 1. Which column contains both sorbitol and a ketose?

o Column D

Question 36

• Refer to the structures in Figure 2 below. Which column contains the structure for adenine?

o A

Test 2 12/6/12 11:46 PM

Question 1 •

o The enzyme of glycolysis that converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate can be categorized into one of six types of enzymes. This enzyme is most appropriately called a(n):

Isomerase Question 2

• Diisopropylphosphofluroridate and sarin are mechanism based inhibitors. They form:

o Covalent bonds with enzymes like acetylcholinesterase Question 3

• On the following plot, N represents the curve for an allosteric enzyme with no allosteric activators or inhibitors added. If an allosteric activator was added, which curve would one obtain?

o Curve B

Question 4

• This small protein can have dramatic effects on the activities of enzymes in response to changes in intracellular calcium ion concentration:

o Calmodulin Question 5

• Pennicillin inhibits a vital enzyme step in bacterial growth. It is highly specific for the enzyme and binds the active site very tightly because:

o It resembles the transition state Question 6

• In the liver, most ingested ethanol is initially converted to which compound and by which enzyme, respectively?

o Acetaldehyde, alcohol dehydrogenase Question 7

• Dennis "the menace" Veere ingested the insecticide malathion. His symptoms of salivating, tearing, sweating, and defecating were caused specifically by the organophosphate toxin binding to which of the following?

o Acetylcholinesterases Question 8

• Allopurinol is a drug used to treat gout. It acts as a suicide inhibitor of which of the following?

o Xanthine oxidase Question 9

• Which of the following statements about allosteric enzymes is CORRECT? o The binding of substrate to any active site affects the other active sites

Question 10

• The most likely effect of a non-competitive inhibitor on an Michaelis-Menten enzyme o Decrease the Vmax

Question 11

• Enzymes catalyze reactions by o Decreasing the free energy of activation

Question 12

• The enzyme hexokinase is o Is inhibited by G-6-P

Question 13

• cAMP

o will bind to the regulatory subunit of PKA Question 14

• Epinephrine binds to α1-receptors in the liver membrane. This binding o Activates phospholipase C

Question 15

• Assume the patient is fasting and then begins to eat a high carbohydrate meal. Following an increase in blood glucose, the message of glucagon is, in part, terminated by

o Increasing protein phosphatase activity in the cell Question 16

• Concerning Mya Sthenia who has myasthenia gravis, she has o Too few acetylcholine receptors

Question 17

• During the fasting state, the release of fatty acids from adipose tissue is increased. At least part of the signal for this release is carried by

o Cortisol from the adrenal medulla Question 18

• Which of the following hormones binds to a receptor in the nucleus or cytosol of target cells?

o Cortisol Question 19

• In the Ras and MAP kinase pathway, the last step in the pathway is catalyzed by MAP-kinase. MAP-kinase

o Phosphorylates a transcription factor Question 20

• In the insulin signal transduction pathway that leads to increases in the diacylglycerol and inositoltrisphosphate second messengers, What is the first signal transduction protein that binds to the IRS?

o Phospholipase C

Question 21

• The following enzyme reaction is catalyzed by Acetyl CoA Carboxylase during fatty acid synthesis: Acetyl CoA + CO2 + ATP = Malonyl CoA + AMP + Pi. This enzyme is most appropriately called a(n):

o Ligase Question 22

• How does the aspirin (acetylsalicylic acid) inhibit prostaglandin endoperoxide synthase (cyclooxygenase)?

o Acetyl group from aspirin is transferred to a serine hydroxide at the active site of COX forming a covalent bond

Question 23

• Phosphorylase kinase activates muscle glycogen phosphorylase by o Phosphorylating a seryl residue on glycogen phosphorylase

Question 24

• Concerning Al Martini who is an alcoholic, assume that the Vmax of cytosolic alcohol dehydrogenase enzyme and the MEOS system are equal in Al's liver and that the KM's are 0.04 mM and 11 mM, respectively. If Al consumes one ounce of alcohol so that his blood level is 6.4 mM,

o The alcohol dehydrogenase enzyme will oxidize more alcohol than the MEOS system

Test 3 12/6/12 11:46 PM

Question 1 Which of the following terms are used to describe the tendency of a reaction to occur when the substrates and products of the reaction are at any concentration?

• Delta G Question 2

• For the enzyme reaction A+ B = C + D, Delta Go' = + 1 kcal/mol. This reaction will proceed spontaneously in a forward direction if:

o The concentration of A is increased 100 fold Question 3

• During muscle contraction: o ATP hydrolysis causes necessary changes in conformation

Question 4

• Oxidative phosphorylation: o Requires the electron transport system

Question 5

• Patients with hyperthyroidism complain constantly of feeling hot and sweaty. All of the following are reasons:

o Thyroid hormone induces many proteins that catalyze the oxidation of fats, carbs and proteins

o Thyroid hormone stimulates the Na+, K+ -ATPase o Thyroid hormone increases the flux through most anabolic pathways o All spontaneous reactions convert some free energy to heat

Question 6

• Which of the following are functions of the citric acid cycle? o Catabolism of carbon structures of some amino acids o Catabolism of acetate groups from acetyl coA o The production of GTP o The production of carbon structures for the synthesis of some amino acids

Question 7

• In the citric acid cycle, a substrate level phosphorylation is catalyzed by:

o Succinyl coA synthetase Question 8

• In contrast to NADH, FAD(2H): o Is very reactive in solution

Question 9

• The anaplerotic reaction that links glycolysis to the TCA cycle: o produces oxaloacetate

Question 10

• Which of the following two enzymes are thought to be the major control enzymes of the TCA cycle?

o A-KG DH and isocitrate DH Question 11

• Wet beriberi results in low peripheral resistance and cardiomyopathy. Both of these symptoms are explained as follows:

o Without thiamine, energy can’t be adequately produced by muscle cells Question 12

• The ATP synthase responsible for most of the ATP synthesis in the body is located:

o On the inner side of the INNER mitochondrial membrane Question 13

• If electrons were removed from α-ketoglutarate and you could watch them move down the electron transport system, the order of movement would be as follows:

o NADH, Complex I, CoQ, Complex III, Cytochrome C, Complex IV, H2O Question 14

• Which of the following statements do help explain the chemiosmotic theory? o ADP and Pi combine to form ATP, this reaction has a positive free energy

change o The only way protons enter the mitochondria is through the ATP

synthase with the concomitant synthesis of ATP

o The inner mitochondria membrane is impermeable to protons o Protons move down a concentration gradient with negative free

energy change Question 15

• A mitochondrion is producing ATP at a constant rate and, then, a chemical uncoupler is added. Compared to before the uncoupler was added:

o More NADH would be oxidized Question 16

• Regarding Cora Nari, which of the following statements about her heart attack and subsequent treatment and effects are true?

o Tissue plasminogen activator causes an increased production of plasmin o Tissue plasminogen activator can be given following a heart attack to dissolve

blood clots o Nitroprusside can be given following a heart attack to dilate blood vessels o Cardiac muscle cells, sperm cells and other active cells have a relatively high

number of mitochondria Question 17

• The cleavage of the high-energy bond of ATP into ADP and Pi is an example of what type of reaction?

o Hydrolysis Question 18

• Delta-G is negative, Delta-Go' is positive. Will the reaction occur spontaneously? o Yes

Question 19

• Which of the following are examples in which ATP is utilized in the body for work? o Contraction of muscle o Phosphorylation of glucose by hexokinase o Maintenance of the Na+ and K+ concentration gradients o Formation of glycosidic bonds to make glycogen

Question 20

• Which of the following are steps during muscle contraction? o ATP is cleaved by an ATPase located on the myosin filament o Presence of calcium enables myosin to bind actin o Thick myosin filaments bind thin actin filaments o The terminal end of a myosin filament binds ATP

Question 21

• The phosphorylation of glucose to glucose-6-phosphate has a Delta Go'of +3.3 kcal/mol. So why does the reaction occur in almost every cell of our body?

o ATP hydrolysis Question 22

• Which of the following statements regarding electron-accepting coenzymes? o FAD accepts electrons as the hydrogen atom o The Delta Go' for the oxidation of NADH by the electron transport

chain is negative o FAD(H2) is synthesized from the vitamin riboflavin o NADH is the reduced for of the coenzyme

Question 23

• Which of the following statements regarding the TCA cycle is CORRECT? o For each acetyl coA entering the cycle, two molecules of CO2 are

produced Question 24

• Which of the following statements regarding the alpha-ketoglutarate dehydrogenase complex are correct?

o It requires FAD as a coenzyme o One of its coenzymes – CoASH – comes from the vitamin pantothenate o CO2 is produced by this complex o It catalyzes the reaction converting A-KG into succinyl coA

Question 25

• Which enzyme complex in the TCA cycle requires the cofactors thiamine pyrophosphate, lipoic acid, CoA, FAD and NAD+?

o A-KG DH

Question 26

• Which of the following statements about the coenzyme FAD is INCORRECT? o FADH2 is an important allosteric inhibitor of the TCA cycle

Question 27

• Which of the following statements about the TCA cycle is CORRECT? o The production of oxaloacetate by pyruvate carboxylase is one of several

anaplerotic reactions of the TCA cycle Question 28

• Which of the following statements regarding the pyruvate dehydrogenase complex are correct?

o When the complex is phosphorylated, it is inactive o Binding of pyruvate to the enxyme complex decreases the activity of the

kinase o High [ADP] stimulates the conversion of pyruvate to acetyl coA o The kinase associated with the PDC is an enzyme that adds phosphate

groups Question 29

• Which of the following statements regarding Complex II are correct? o Neither the single of 2-electron forms of FAD dissociate from the enzyme o This is one means by which the TCA cycle is linked to the ETC o Succinate dehydrogenase is embedded in the inner mitochondrial

membrane o The transfer of electrons from FAD(2H) to the ETC results in the

synthesis of 1.5 ATP Question 30

• Which of the following are in the correct sequence? o NADH DH; Cytochrome b-c1; Cytochrome C; Cytochrome oxidase

Question 31

• All of the following can act as "uncouplers": o Brown adipose tissue

o Proton ionophores o Themogenin (in infants) o Thyroid hormone

NOT cyanide – it is an inhibitor Question 32

• A patient suffers a heart attack due to the blockage of an artery. The heart cells downstream from the blockage will receive less oxygen which will in turn cause

o [NADH] increase Question 33

• A patient has hyperthyroidism. Compared to normal, you would expect that the electron transport chain would

o Increase electron flow through the chain Question 34

• Assume standard biological conditions and that all the enzymes are present to catalyze the reactions. Given the following data: Glucose + Pi = glucose-6-P + H2O, ΔGo′ = +3.3 kcal/mol ATP + H2O = Pi + ADP, ΔGo′ = -7.0 kcal/mole Calculate the ΔGo′ for the following reaction and determine whether the reaction is spontaneous: Glucose + ATP --> Glucose-6-P + ADP

o -3.7 kcal/mol and spontaneous

Test 4 12/6/12 11:46 PM

Question 1 • The enzyme that controls the rate at which metabolites flow through glycolysis is:

o PFK-1 Question 2

• Which of the following is not a component of the Cori cycle: o aerobic glycolysis

Question 3

• Your patient comes to the emergency room with a bleeding ulcer. She has felt bad for several days. She suffers from COPD smoking 2 packs per day. She appears cyanotic. You expect a:

o High blood lactate Question 4

• If palmitoyl CoA undergoes beta-oxidation, the products will be: o 7 NADH + 7 FADH2 + 8 Acetyl coA

Question 5

• The following graph shows the increase of blood acetoacetate, beta-hydroxybutyrate, glucose and free fatty acids during a fast. Which of the following is CORRECT?

o

o Answer

a. Curve A represents glucose

b.

c. Curve B represents acetoacetate

d. Curve C represents glucose?

e. Curve A represents beta-‐hydroxybutyrate

Question 6

• Medium chain acyl CoA (MCAD) deficiency results in: o Decreased levels of liver ATP during a fast

Question 7

• All other things being constant, an increase in stress hormones would result in an increase in:

o Blood amino acids for gluconeogenesis Question 8

• During the series of events following increase in insulin, all of the following occur: o Insulin binds its receptor, causing the autophosphorylation of receptor

subunits o Active protein kinases can cause the induction/repression of genes o Glucagon-stimulated phosphorylation is reversed by insulin effects o Phosphorylation results in more glucose transporters in the adipose tissue

Question 9

• Which of the following are results of insulin binding to its receptor on a muscle cell? o The receptor undergoes a change in conformation o The receptor autophosphorylates tyrosyl residues o Phosphorylation of the IRS is increased o More glucose transporters are inserted into the membrane

Question 10

• In a patient with NIDDM who has started taking a sulfonylurea drug, which of the following is part of the mechanism?

o The sulfonylurea drug increases [intracellular Ca+2] Question 11

• Which of the following statements about glycogenolysis and glucose metabolism is TRUE?

o Liver glycogenolysis and glycolysis are not usually active at the same time Question 12

• Which of the following events helps in the incorporation of blood glucose into muscle glycogen?

o

c. Branching enzyme produces alpha-‐1,4-‐glucosidic bonds

d. ATP is a substrate for glycogen synthase?

e. Hydrolysis of pyrophosphate makes the overall reaction exergonic

Question 13

• All of the following activate muscle phosphorylase EXCEPT: o Protein phosphatase

Question 14

• An absence of liver glucose-6-phosphatase is known as: o Von Gierke’s

Question 15

• Which of the following glycolytic intermediates and enzymes are in the CORRECT sequence?

o Hexokinase; PFK-1; DHAP; PEP Question 16

• Which of the following glycolytic enzymes produce ATP during glycolysis o 3-phophoglycerate kinase

Question 17

• The LDH reaction is reversible. Which of the following is not a substrate for this rxn? o PEP

Question 18

• In a cell with mitochondria, NADH is produced during glycolysis. Since NADH cannot cross the mitochondrial membrane, the electrons of NADH are transferred to another compound which can cross the mitochondrial membrane. The compound is

o Malate Question 19

• The activation of fatty acids involves all of the following players EXCEPT: o

a. ATP

b. Fatty acyl CoA synthetase

e. Fatty acylcarnitine

Question 20

• Regarding the CPT I and the CPT II reactions, which of the following are true? o The reaction is necessary before activated FA can pass into the matrix from

the cytosol o CPT 1 is embedded in the outer mitochondrial membrane o CPT II transfers the acyl group from acylcarnitine o CPT I causes the transfer of FA from acyl-coA to carnitine

Question 21

• Which of the following are TRUE of beta-oxidation? o Even chain FA can be completely converted to acetyl coA o For each NADH that is formed, 2.5 ATP are generated o The overall B-ox of a 16 carbon fatty acyl coA to 8 acetyl CoAs yields 28

ATP o The B-ox of an odd chain FA would yield a propionyl CoA

Question 22

• Regarding the synthesis of ketone bodies, which of the following is TRUE? o HMG CoA is an intermediate that is converted into acetoacetate

Question 23

• Increased blood insulin specifically plays a major role in all of the following: o Glucose stored as glycogen in liver and muscle o Conversion of glucose to TG in liver o Amino acid uptake and protein synthesis in skeletal muscle o Stimulation of transport of glucose into muscle and adipose tissue

Question 24

• In the synthesis of Insulin, which of the following is TRUE? o Glucose is a major regulator of insulin release o Cleavage of proinsulin to insulin yields a c-peptide o The chains of insulin are held together and in active conformation by disulfide

bridges o The A chain of insulin is shorter than the B chain

Question 25 • All the following are important in the glucagon second messenger cascade:

o Glucagon binds causing the dissociation of GDP from and the association of GTP with the G-protein

o Adenylate cyclase catalyzes the conversion of ATP to cAMP o Phosphodiesterase catalyzes the conversion of cAMP to AMP o The cAMP binds to PKA regulatory subunits, releasing catalytic subunits

Question 26

• In liver and muscle, glycogen degradation is characterized by all of the following:

o The yielding of G-1-P residues by the enzyme glycogen phosphorylase o Acivity of a 4:4 transferase to ensure the debranching o The activity of an alpha-1,6 glucosidase that yields free glucose residues o The use of inorganic phosphate by glycogen phosphorylase

Question 27

• Which of the following is NOT true? o E inhibits glycolyysis of glucose in muscle cells

Question 28

• A bodybuilding enthusiast injected insulin and tried to work out for several hours. He continuously ingested the sports drink containing salts but no glucose, fatty acids, or protein. He passed out and went into a coma. All of the following contributed to his coma

o Insulin inhibited glycogenolysis o Insulin inhibited gluconeogenesis o The insulin inhibited hormone sensitive lipase o The exercise used a lot of glucose

Question 29

• Concerning Otto shape, during his long distance run the change in the concentration of AMP ensures the increased uptake of fatty acyl CoA into his muscle mitochondria. This happens because the AMP-dependent protein kinase catalyzes the phosphorylation of

o Acetyl CoA carboxylase

Test 5 12/6/12 11:46 PM

Question 1 • The enzyme phosphofructokinase-2/fructose-2,6-bisphosphatase plays a key role

in the control of glycolysis exerted by the insulin to glucagon ratio. If the insulin to glucagon ratio increases, phosphofructokinase-2/fructose-2,6-bisphosphatase in the liver would:

o Become less phosphorylated and PFK-2 would become more active Question 2

• During a fast, the liver enzyme pyruvate kinase becomes: o Less active and more phosphorylated

Question 3

• This patient has been taking dexamethasone for severe asthma for several weeks. She has developed hyperglycemia and muscle weakness. A partial explanation of these symptoms might be:

o Induction of PEPCK Question 4

• The pentose phosphate pathway can, without help from glycolysis or gluconeogenesis, perform the following:

o synthesis of NADPH from G-6-P o synthesis of R-5-P from G-6-P o R-5-P from F-6-P and G-3-P o F-6-P and G-3-P from R-5-P (reversible)

Question 5

• Which of the following would require NADPH? o Reduction of antioxidant vitamins o Detox reaction that use P450 o Reductive biosynthesis of cholesterol o Biosynthesis of palmitate o B-ox of FA

Question 6

• A patient takes sulfa drugs for the first time and develops hemolytic anemia. The other blood cells appear normal. The best explanation is:

o Other cells have higher [NADPH] Question 7

• After ingestion of a high carbohydrate meal, all of the following are true: o Glucose transport into muscle and adipose tissue is increased o Glucose uptake and utilization by adipose tissue is increased o Glucose storage in glycogen is increased o Glycolysis in the liver is increased

Question 8

• When glucagon binds to a liver cell, o adenylate cyclase is activated

Question 9

• After a 24 hour fast, the maintenance of blood glucose is largely a result of the change in the insulin to glucagon ratio. All of the following help to explain this:

o More free FA is mobilized from adipose tissue o More glycerol is mobilized from adipose tissue o More acetyl CoA is produced from FFA in the liver o Acetyl CoA activates pyruvate carboxylase

Question 10

• Bob was brought to the emergency room. His wife said that he was a 33 year old and had IDDM (Type I). He had told her last night that he had forgotten whether he had taken his injection. Since he couldn't remember, he gave himself another injection. His blood glucose was 25 mg/dL. At the present time and compared to a normal person, Bob has:

o Low blood ketone bodies Question 11

• Which of the following enzymes is NOT part of the pathway for converting carbon atoms in glucose to carbon atoms in free fatty acids in the liver?

o Pyruvate DH o Pyruvate carboxylase o Citrate lyase o Citrate synthase

Question 12

• All of the following are intermediates in the synthesis of triacylglycerol from glucose following a high carbohydrate meal:

o DHAP, Gol-3-P, Phosphatidic acid and diacylglycerol Question 13

• Ginny has been fasting (500 kcal/day) for several days. All of the following would be increased:

o Cyclic-AMP in adipose tissue o The activity of hormone sensitive lipase in adipose tissue o Amount of FFA bound to albumin in the blood o Fatty acyl CoA entering the liver mitochondria

Question 14

• Phosphatidylethanolamine is converted to phosphatidylcholine in an enzyme reaction that transfers three activated methyl groups to the ethanolamine converting it to phosphatidylcholine. This reaction requires the cofactor:

o S-adenosylmethioine Question 15

• Which of the following is NOT a glycerophospholipid commonly found in cell membranes:

o phosphatidylglycine Question 16

• You are a fourth year medical student on rounds in the pediatric unit. The patient is a premature infant with respiratory distress syndrome. The attending physician asks the students present to explain one molecular cause of the disease. Student 1 says that the infant is not making enough dipalmitoylphosphatidylcholine. Student 2 says that the infant is not able to make enough lecithin. Student 3 says that the infant is not able to make enough sphingomyelin. Your best answer is:

o 1 and 2 are correct Question 17

• During gluconeogenesis, an increased concentration of acetyl-CoA in the liver cell will activate:

o Mitochondrial pyruvate carboxylase Question 18

• When pyruvate carboxylase and phosphoenolpyruvate carboxykinase are active, futile cycling is prevented by:

o Phosphorylation and inactivation of pyruvate kinase by glucagon via cAMP Question 19

• Gluconeogenesis ends with the conversion of fructose-1,6-bisphosphate to glucose in a series of three enzymatic steps. Which of the following statements regarding these enzymes is TRUE:

o Two release inorganic phosphates and the other’s reverse is in glycolysis Question 20

• An increase in the insulin/glucagon ratio would lead to______________ and a(n) __________conversion of phosphoenolpyruvate to pyruvate.

o Dephosphorylation of pyruvate kinase and increase in the PEP to pyruvate Question 21

• The hexose monophosphate shunt is: o Found in the cytosol of all cells

Question 22

• If a cell needed to make exactly twice the amount of NADPH as ribose-5-phosphate, which glycolytic substrate(s) would be most efficient:

o G-6-P Question 23

• Glutathione is continuously being reduced and oxidized. Which group on the molecule is actually being reduced and oxidized:

o Sulfhydryl group of cysteine Question 24

• A pathway exists that uses substrate(s) from the glycolytic pathway to produce reducing agents that remove H2O2 from the cell. Al of the following enzymes are used by that pathway:

o 6-phosphogluconate DH o G-6-P DH o Glutathione reductase o Glutathione peroxidase

Question 25

• A person fasts for 12 hours and then eats a high protein meal. About 45 minutes later their blood is analyzed. Compared to blood levels before ingestion:

o Insulin and glucagon will be higher and gluconeogenesis is active Question 26

• Regarding dietary glucose entering the liver following a high caloric, high carbohydrate meal. Which of the following statements are true:

o Some glucose is converted to glycerol phosphate, stored as glycogen, used aerobically and anaerobically in glycolysis

Question 27

• When going from the fed state to the fasted state, the activity of the glycolytic and gluconeogenic pathways are changed. Part of the mechanism for this change is:

o Increase in F-2,6-BPase Question 28

• You meet your patient in the emergency room. She forgot that she took her first shot of insulin last night and so she took a second shot. She is now in a hypoglycemic coma. Which of the following is contributing to the low blood sugar:

o insulin inhibited F-1,6-BPase in the liver Question 29

• Both acetyl CoA and the acyl carrier protein o Contain phosphopantetheine reactive groups

Question 30 • Which of the following is NOT an intermediate in the synthesis of triaclglycerol

from glucose-6-phosphate and fatty acids in adipose tisssue: o Glycerol

Test 6 12/6/12 11:46 PM

Question 1 1 out of 1 points During fasting, all of the following would tend to increase the flux through gluconeogenesis EXCEPT:

Answer

Selected Answer: d.

The concentration of fructose-‐2,6-‐bisphosphate rises

Question 2 1 out of 1 points All of the following contribute to the increase in ketone body synthesis in the liver during fasting EXCEPT:

Answer

Selected

Answer:

a.

The increased insulin to glucagon ratio activates lipoprotein lipase

in adipose tissue

Question 3 1 out of 1 points A patient with type I diabetes has come to the emergency room with ketoacidosis. All of the following might help to explain why her ketones are high EXCEPT:

Answer

Selected Answer: e.

Carnitine deficiency

Question 4 1 out of 1 points The pKa for ammonium ion is about 9.4 and the pH of blood is about 7.4. The ratio of ammonia to ammonium ion (ammonia/ammonium ion) in blood is about:

Answer

Selected Answer: a.

1/100

Question 5 0 out of 1 points Which of the following enzyme reactions takes place during the synthesis of urea from ammonium ion and glutamate?

Answer

Selected Answer: e.

Argininosuccinate = arginine + urea

Question 6 1 out of 1 points All of the following would be expected to increase the activity of the urea cycle EXCEPT:

Answer

Selected Answer: a.

Antibiotics

Question 7 1 out of 1 points Which of the following is an essential amino acid?

Answer

Selected Answer: c.

Valine

Question 8 0 out of 1 points The products of the catabolism of cysteine are:

Answer

Selected Answer: d.

Serine and sulfate

Question 9 0 out of 1 points All of the following are substrates or products of the phenylalanine hydroxylase reaction EXCEPT:

Answer

Selected Answer: e.

O2

Question 10 0 out of 1 points

You suspect that your 12 year old male patient has an inborn error in methionine metabolism. It may be that cystathionine synthase is deficient. If this is true, he should have high serum concentrations of:

Answer

Selected Answer: d.

α-‐ketobutyrate

Question 11 0 out of 1 points As a result of having the disease phenylketonuria, phenyl ketones are found in the urine. The best explanation for this is:

Answer

Selected

Answer:

d.

Phenylalanine hydroxylase is present and tyrosine hydroxylase is

absent

Question 12 0 out of 1 points Following a meal, glucose will be stored in liver glycogen because:

Answer

Selected

Answer:

c.

Glycogen phosphorylase A will be inactivated by phosphorylation

by protein kinase A

Question 13 0 out of 1 points The enzyme acetyl CoA carboxylase is activated following an increase in:

Answer

Selected Answer: b.

Protein kinase A activity

Question 14 1 out of 1 points The delivery of free fatty acids from lipoproteins into adipose tissue cells will be increased by:

Answer

Selected Answer: e.

Insulin

Question 15 0 out of 1 points Compared to a normal person, a patient with diabetes Type II:

Answer

Selected Answer: c.

Will have adipose tissue cells that are just as responsive to insulin


During a fast, muscle protein is catabolized to free amino acids. All of the following scenarios occur EXCEPT:

Answer

Selected Answer: d.

Alanine is used for gluconeogenesis in the muscle

Question 17 1 out of 1 points Which of the following statements about glutamate is NOT true:

Answer

Selected Answer: e.

It can transfer it's amino group to citrulline in a one step reaction

Question 18 0 out of 1 points The urea cycle is regulated by:

Answer

Selected Answer: c.

Malonyl CoA


The carbon structure of this amino acid can be converted in a single enzyme step into an intermediate in either the TCA cycle or the urea cycle:

Answer

Selected Answer: d.

Glutamate

Question 20 0 out of 1 points Which of the following is an essential amino acid:

Answer

Selected Answer: e.

Asparagine

Question 21 1 out of 1 points Serine is a nonessential amino acid. The precursor in glycolysis or the TCA cycle from which serine is made is:

Answer

Selected Answer: d.

3-‐phosphoglycerate


All of the following amino acids are glucogenic EXCEPT:

Answer

Selected Answer: a.

Leucine

Practice Study Guide 12/6/12 11:46 PM

Question 1 • The pH of a solution is 7.4. If half of the hydrogen ions are removed, the new pH

would be: o 7.7

Question 2

• The pKa for ammonium ion is 9.3. At a blood pH of 7.3, there is: o One hundred more times ammonium ion vs ammonia

Question 3

• Phenobarbital is a weak acid with a pKa = 7.1. Its acid form (protonated form) is readily reabsorbed from the kidney filtrate into the blood. Its charged form (salt form) is not reabsorbed from the kidney filtrate into the blood, but rather, finds it way to the urine. Which of the following would you give to an intoxicated patient in order to remove phenobarbital from her system? [Hint! Use the Henderson-Hasselbalch equation for phenobarbital and consider the affect of each of the following.

o NaHCO3 Question 4

• Which of the following do you expect to see in a patient with metabolic acidosis with no respiratory compensation?

o Decrease of [HCO3-] in the blood

Question 5

• Refer to the following Figure. In which row is a structure for lysolecithin found?

o o Row D

Question 6

• Refer to the following Figure . In which row is a structure for triacylglycerol found?

• • Row A

Question 7

•

o Refer to the following Figure for Question 7.

Which answer is correct:

Column C shows Tymine and pyrimidine ring Question 8

• Arichidonic Acid is o Is depicted as 20:4delta 5, 8, 11, 14

Question 9

• This amino acid has three pKa's and an isoelectric point of 3.1. The amino acid is: o Glutamate

Question 10

• Which of the following will migrate the fastest toward the positive end of an electric field?

o Alanine at a pH of 11.0 (look at pH not charge) Question 11

• Which of the following best describes the net charge of the R groups of the following amino acids at the designated pH?

o Histidine: positively charged at a pH of 4.1 Question 12

• What will be the net charge of the protein below at physiologic pH (7.4)? NH3+-Ala-Phe-Glu-Lys-Arg-Pro-COO-

o +1

Question 13 • If a polypeptide portion of a protein can assume the same stable conformation

that it does in the native protein, it can be called a: o Domain

Question 14

• Which of the following characterize the a-helix secondary structure of proteins? o Hydrogen bonds between oxygens and nitrogen atom four residues apart

Question 15

• HbA1C is o A measure of blood glucose during the past 6 weeks

Question 16

• As you read about, Michel Sichel just experienced a sickle cell crisis. Which of the following statements about sickle cell anemia is TRUE?

o Amino acid substitution results in a hydrophobic knob or area Question 17

• When lactate is oxidized to pyruvate: o Two electrons and one proton are transferred to NAD+

Question 18

• The drug allopurinol is used to treat gout. Which of the following common biological pathways is inhibited by the drug?

o The conversion of GMP to urate Question 19

• To stabilize the transition state complex, which of the following must be lowered? o Activation energy

Question 20

• The following enzyme reaction is an example of a(n)? Glucose + ATP = Glucose-6-phosphate + ADP

o transferase

Question 21 • During muscle contraction, calcium is released from the endoplasmic reticulum. An

increase in glycogenolysis is initiated when calcium binds to o Calmodulin

Question 22

• If an enzyme is described by the Michaelis-Menten equation, a competitive inhibitor will:

o Increase the Km but not change the Vmax Question 23

• You have isolated the control enzyme phosphofructokinase-1. When you plot the initial velocity vs. substrate concentration, an S-shaped curve results. This reflects

o Cooperative binding Question 24

• An apoenzyme o Protein portion of the enzyme without cofactors

Question 25

• As a result of insulin binding to the insulin receptor, the GRB protein binds to the IRS. The binding of the GRB adaptor protein occurs because the IRS contains

o A phosphorylated tyrosyl residue Question 26

• When epinephrine binds to alpha-1 receptors, one result is o The ER releases calcium ions

Question 27

Concerning Mya Sthenia who has myasthenia gravis, her chemical messenger system differs from a normal person because she has to:

o Few acetylcholine receptors in the postsynaptic membrane Question 28

• When epinephrine binds to a b-receptor on the liver membrane and activates a Gαs signal transduction protein,

o The Gas protein dissociates into an aB-complex and Y-subunit Question 29

• Given the following reactions: A + H20 = B + C Delta-Go' = + 11 kcal/mol D + H20 = B + G Delta-Go' = + 3 kcal/mol K + H20 = B + L Delta-Go' = -7 kcal/mol J + H20 = B + M Delta-Go' = -5 kcal/mol Which of these reactions would be exergonic when proceeding from left to right?

o K+M = J+L Question 30

• NAD+, FAD, and FMN are all cofactors for: o Oxaloreductases

Question 31

• All of the following would help to explain why ischemia would cause a failure of the left ventricular muscle to eject a normal amount of blood EXCEPT:

o Without oxygen, intracellular calcium concentrations cannot be maintained at a high enough level

Question 32

• For the reaction A = B + C, the concentration of A is 1 mM, the concentration of B is 1 mM and the concentration of C is 2 mM. Also, standard free energy change for the reaction under biological conditions is Delta-Go' = 0 kcal/mole and free energy change for the reaction is Delta-G = - 3.7 kcal/mole. If the concentration of C is lowered to 1 mM,

o The delta G will become more negative Question 33

• When muscles contract, a chain of events result in greater activity by the TCA cycle. All of the following are links in that chain:

o The ADP concentration increases o The proton gradient across the mitochondrial membrane is diminished

o The ETC produces more water o [NADH] decreases and [NAD+] increases

Question 34

• The TCA cycle: o Is controlled by the calcium ion, ADP/ATP ratio and [NADH]

Question 35

• Which of the following statements regarding the four "dehydrogenases" of the TCA cycle are correct?

o These are enzymes that remove electrons in the form of hydrogen from various structures and transfer them to others

o At least one catalyzes the “rate-limiting steps” of the TCA cycle o NAD+ and FAD are the electron-accepting coenzymes f o At least one catalyzes a reversible reaction

Question 36

• The rate at which pyruvate from glycolysis is used by the TCA cycle to produce energy is regulated by pyruvate dehydrogenase. During muscle contraction, this enzyme is:

o Activated by ADP increases Question 37

• If a muscle begins to work hard, the ATP concentration of the cell will drop. In turn, the pyruvate dehydrogenase reaction will be activated. Which of the following mechanisms will play a role, either directly or indirectly, in this activation?

o Increase Ca+2 will cause dephosphorylation and activation of the enzyme o Increased ADP will inhibit phosphorylation of the enzyme and activate it o Increased ADP will activate ATP synthase and lower the proton gradient o A lower proton gradient will increase the utilization of NADH

Question 38

• The chemiosmotic theory holds all of the following: o The inner mitochondrial membrane is impermeable to protons o In the absence of a proton motive force, ATP will not be synthesized

o The electrochemical potential comes from both the electrical potential and the proton concentration gradient

o Electrons are passed from one carrier to the next as protons are pumped across the inner mitochondrial membrane

Question 39

• When the electron transport chain is exposed to cyanide, o [NADH] increases

Question 40

• Which of the following can increase the permeability of membranes to protons and thus decrease ATP synthesis while increasing the consumption of O2

o A proton ionophore Question 41

• During aerobic glycolysis, the conversion of glucose to pyruvate, what is the net production of energy in ATP equivalents?

o 7 ATPs Question 42

• You have a patient who eats hard candy throughout the day. The patient also has dental caries. Which of the following is part of the correlation between eating candy and dental caries?

o Anaerobic metabolism produces lactate and lowers the pH below 5.0, dissolving the bone

Question 43

• When undergoing strenuous exercise the Cori Cycle is functioning. Which of the following compounds is being delivered to muscle tissue as part of this Cycle?

o Glucose Question 44

• Anemia, hemorrhage, and chronic obstructive pulmonary disease can all cause metabolic acidosis. The best explanation is that the lack of oxygen causes :

o A decrease in oxidative phosphorylation so the cells have to rely upon anaerobic glycolysis

Question 45

• All of the following are substrates or products of the fatty acyl CoA synthetase reaction EXCEPT:

o ADP Question 46

• In the fasting state, more ketone bodies are made in the liver because: o More triacylglycerol is hydrolyzed in adipose cells

Question 47

• Free fatty acids are able to travel from adipose tissue to muscle or liver o Bound to serum proteins

Question 48

• Which of the following is TRUE following β-oxidation in the liver? o The formation of propionyl CoA could lead to the production of glucose from

B-oxidation o The formation of acetyl CoA could lead to ketone body synthesis o Acetyl CoA could be used for synthesis of HMG CoA o Acetyl CoA might be oxidized by the TCA cycle

Question 49

• All other things being constant, an increase in glucagon would result in an increase in o Beta oxidation in the liver

Question 50

• Your patient has an insulinoma. 6 hours after a meal, her blood: [C-peptide] would be elevated

Question 51

• Concerning Anne Sullivan who has suffered from NIDDM for five years. Which of the following statements is true?

o Her rate of gluconeogenesis is abnormal Question 52

• Insulin is secreted by the B-cells of the pancreas into the hepatic portal vein. Which of the following regarding insulin synthesis is true:

o the active form of insulin is composed of two polypeptide chains linked by two interchain disulfide bonds

o the A-chain has an intrachain disulfide bond o insulin is synthesized as a preprohormone which is converted to proinsulin o cleavage of proinsulin yields a C-peptide

Question 53

• A woman body builder passed out and went into a coma while lifting weights. When she arrived at the emergency room, her blood glucose was 24 mg/dL (normal - 70 - 105 mg/dL). Her friend said that she had injected 60 units of regular (short acting) insulin before each meal for the last 5 meals. This is at least 4 times normal basal secreting of insulin. Insulin had all of the following effects:

o Increased glucose transport into muscle o Decreased glycogen phosphorylase activity in muscle o Decreased gluconeogenesis in liver o Decreased glycogen phosphorylase in liver

Question 54

• In liver and muscle, glycogen synthesis is characterized by all of the following: o The phosphorylation of glucose o The formation of UDP-glucose o The actions of a branching enzyme, to ensure branching o The conversion of G-6-P to G-1-P by phosphoglucomutase

Question 55

• Which of the following statements is CORRECT regarding the function of glycogen in liver and skeletal muscle?

o Liver glycogen is the first and immediate source of glucose for the maintenance of blood glucose levels

Question 56

• What is the effect of increases in protein kinase A activity upon the activity of glycogen synthase and glycogen phosphorylase?

o Phosphorylation and activation of glycogen phosyphorylase

Question 57

• The activity of the oxidative portion of the pentose phosphate pathway is controlled by the:

o Concentration of NADPH in the cytosol Question 58

• NADPH is used for o Reductive biosynthesis of FA

Question 59

• During the Korean War, 10 percent of black servicemen given the drug primaquine developed drug-induced hemolytic anemia. These men had only 15 percent of the normal somatic activity of

o G-6-P DH Question 60

• All of the following enzymes and metabolites are found in the pathway for the reduction of HOOH except

o NADH + H+ Question 61

• Liver cells are able to release glucose to the circulation from both glycogen and gluconeogenesis. Which of the following enzymes is important to both of these processes?

o Glucose-6-Phosphatase Question 62

• After strenuous muscle activity, lactate produced from anaerobic glycolysis is recycled in the liver by being ____________________ in a reaction catalyzed by lactate dehydrogenase.

o Oxidized by NAD+ to form pyruvate Question 63

• A person eats a meal and then watches TV or sleeps for the next 16 hours of a fast. At 16 hours, what is the source of their blood glucose?

o 50/50 from glycogenolysis and gluconeogenesis Question 64

• Which of the following occurs during prolonged fasting (starvation)? o As a fast progresses, tissues rely predominantly on fuels derived from adipose

triacylglycerols Question 65

• Which of the following is an essential fatty acid? o Linoleic

Question 66

• S-adenosylmethionine is important in the synthesis of o Phosphatidylcholine from phosphatidylethanolamine

Question 67

• Palmitoyl CoA and other activated long chain fatty acids can be elongated two carbons at a time by a series of reactions that occur in the:

o ER Question 68

• An infant is born prematurely and has respiratory distress syndrome. All of the following will be low

o Dipalmitoylphosphatidylcholine o Phosphatidyl glycerol o Surface active proteins o Lung surfactant

Question 69

• The pathway for the synthesis of glycogen from portal blood glucose in the liver: o Is inhibited by high cAMP

Question 70

• A patient with type I diabetes has come to the emergency room with ketoacidosis. All of her serum samples are opalescent, ie, they scatter light.

Compared to a normal person, all of the following probably contributed to this abnormal serum:

o Capillaries don’t have as much lipoprotein lipase activity o Adipose hormone sensitive lipase is more active o More VLDL is being synthesized in the liver o The [cAMP] of adipose tissue is high

Question 71

• Your patient sufferers from type I diabetes. Compared to a normal person your patient will have

o Decreased lipoprotein lipase activity Question 72

• The following are all effects of insulin EXCEPT o Stimulation of acetyl coA carboxylase o Stimulates adipose cells to synthesize and secrete LDL o Stimulates G-6-P DH o Increase GLUT 4s in adipose cell membranes

Question 73

• What is the name of the cofactor for AST, ALT, or any other transamination reaction?

o PLP Question 74

• Your patient has hepatitis A which has developed into hepatic encephalopathy. All of the following might be helpful:

o low protein diet o antibiotics o lactulose o enemas

Question 75

• Which of the following reactions takes place in the mitochondria during the synthesis of urea from ammonium ion and glutamate?

o Ornithine transcarbamoylase

Question 76

• Alanine aminotransferase (ALT) transfers an amino group from alanine to o A-KG

Question 77

• Which of the following is an essential amino acid? o Methionine

Question 78

• You suspect that your 12 year old male patient has an inborn error in methionine metabolism. His methionine levels are low and his homocysteine levels are high. A liver biopsy indicates that his cystathionine synthase and cystathionase levels are normal. This patient may have a deficiency:

o Of B12, folic acid, pathway of methyl cobalamin and N5-methyl tetrahydrofolate

Question 79

• The catabolic products of isoleucine, methionine, and valine all enter into the TCA cycle or glycolysis as

o Succinyl CoA Question 80

• The patient-has normal cystathionine levels and normal vitamin B12 metabolism. She has an inborn error in the pathway for tetrahydrofolate production. Which of the following would be at a lower concentration when compared to a healthy individual?

o Methionine Question 81

• Ketoacidosis refers to the metabolic acidosis caused by the overproduction of ketoacids. The classic form of ketoacidosis is uncontrolled diabetes mellitus. All of the following would occur in a patient suffering from a diabetes-induced metabolic acidosis (diabetic ketoacidosis):

o Deep/rapid breathing causes a decrease in the partial pressure of CO2 in blood

o Removal of CO2 through depe, rapid breathing results in a pH rise of blood

o Endogenous acid production rises, net acid excretion cannot keep up and bicarb lost in buffering is not replace, so [bicarb] decreases

o The fall in insulin causes fat cells to liberate FA, flooding the hepatocytes Question 82

• Sickle cell disease results from a point (missense) mutation of the b-globin of: o Valine for glutamate

Question 83

• Aldolase is classified as a(n) o Lyase

Question 84

• When the blood concentration of insulin is increased, less glucagon is produced and there is an increase in

o the activity of cAMP phosphodiesterase Question 85

• The ΔG and ΔG0! Both refer to the free energy change in a steady state reaction. Steady state means that the concentrations of substrates and products are fixed or constant. All of the following statements about ΔG and ΔG0! Are true EXCEPT

o delta G0f for a specific reaction can have many values (PSYCH!) Question 86

• Your patient is an alcoholic with a buildup of a-ketoacids and symptoms of wet beriberi. All of the following might be part of a scenario that would explain why peripheral vessels dilate and cardiac muscles loose their contractility EXCEPT

o Muscle needs ATP to contract o Most ATP is produced in oxidative phosphorylation o NADH and FADH2 are produced in the TCA cycle o The TCA cycle needs TPP to function

Question 87

• In the muscle, all of the following are part of the pathway whereby increased epinephrine causes an increase in the glycolytic pathway

o Increased binding of GTP to G-protein o Activation of cAMp cascade o Increased phosphorylation of enzymes by PKA o Increased binding of F-2,6-BPase to PFK-1

Question 88

• All of the following help to explain the mechanism for releasing insulin from β-cells in response to the concentration of blood glucose

o The important regulator of glycolysis in B cells is [glucose] reacting with glucokinase

o ATP is made in proportion to the rate of glycolysis o Rate of K leaving the cell through a potassium channel is a major

determinant of the polarization of the cell membrane o ATP inhibits the K channel, the more ATP, the less K leaving and less

polarized the cell becomes Question 89

• All of the following statements about the pentose phosphate pathway are true o its two functions are to produce NADPH and R-5-P o it uses G-6-P as a substrate when producing NADPH and CO2 o G-6-P DH is the control enzyme that is regulated by [NADPH] in the cell o It is producing more than twice as much NADPH as R-5-P, it produces

Ghyde-3-P and F-6-P Question 90

• The most important control step in gluconeogenesis is fructose-1,6-bisphosphatase. All of the following statements are true

o When insulin is high, F-1,6-BPase converts F-2,6-BP to F-6-P o During a fast or exercise, F-1,6-BPase is active b/c F-2,6-BP is absent o Glycolysis or gluconeogenesis can’t be active at the same time o F-2,6-BP in the liver is made by PFK-2, which is inhibited by cAMP

Question 91

• When the concentration of epinephrine or glucagon is high, they bind to receptors on adipose cell membrane and all of the following can be expected to occur

o caMP cascade activates hormone sensitive lipase o triacylglycerol is hydrolyzed to FFA and glycerol o FFA are carried to most tissues by albumin o FA are activated, enter the mitochondria and oxidized by B-ox and TCA

Question 92

• This patient has a deficiency of argininosuccinate lyase and has very high concentrations of blood glutamine and ammonium ion. You could treat her with all of the following

o Low protein diet o Arginine supplementation o Benzoic acid tablets o Oral doses of phenylbutyrate

Question 93

• Your patient has a high serum homocysteine level and a defect in the enzyme that transfers one-carbon units from N5-methyltetrahydrofolate to form methylcobalamin (B12). The greatest change from normal would be in the rate of conversion of

o Homocysteine to methionine

bcmb tests

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