Biochem II Exam 2

Topic 5 - Eicosanoid Metabolism

5-Hydroperoxyeicosatetraenoic acids can be used to synthesize:

a.

leukotrienes

b.

tetrahydrofolate

c.

carbamoyl phosphate

d.

leucine

a.

leukotrienes

5-Lipoxygenase is responsible for the biosynthesis of ________________.

a.

Leukotrienes

b.

Prostacyclin

c.

Thromboxanes

d.

Prostaglandins

a.

Leukotrienes

Aspirin will inhibit which of the following reaction pathways?

a.

arachidonic acid to lipoxins

b.

linoleate to arachidonic acid

c.

arachidonic acid to leukotrienes

d.

arachidonic acid to thromboxanes

d.

arachidonic acid to thromboxanes

Biosynthesis of which of the following molecules uses lipoxygenase pathway?

a.

Leukotriene A4

b.

Prostaglandin G2

c.

Thromboxane A2

d.

Prostacyclin

a.

Leukotriene A4

Does aspirin have anti-platelet effects?

a.

No

b.

Yes

b.

Yes

Eicosanoids are derived from the following precursor:

a.

Eicosapentanoic acid

b.

Arachidonic acid

c.

Glycerol

d.

Glutamic acid

b.

Arachidonic acid

How aspirin modulates the activity of the cyclo-oxygenase enzyme?

a.

By acetylation of the seryl hydroxyl group of the enzyme

b.

By dimethylation of the hydroxyl group of the methionine residue of the enzyme

c.

By methylation of the hydroxyl group of tyrosine residue of the enzyme

d.

By addition of a sulfhydryl group to the hydroxyl moiety of serine residue of the enzyme

a.

By acetylation of the seryl hydroxyl group of the enzyme

The enzyme PGH synthase contains two different functionalities, a __________ that uses two molecules of oxygen as substrates and __________ which performs a 2 electron reduction.

a.

cyclooxygenase; peroxidase

b.

cyclooxygenase; reductase

c.

dioxygenase; peroxidase

d.

lipoxygenase; peroxidase

a.

cyclooxygenase; peroxidase

What classification is given to the following molecule?

a.

a leukotriene

b.

a prostaglandin G derivative

c.

a prostaglandin E derivative

d.

a thromboxane

a.

a leukotriene

What eicosanoid metabolic reaction involves the enzyme phospholipase A2?

a.

arachidonic acid to leokotrienes

b.

arachidonic acid to membrane phospholipid

c.

arachidonic acid to prostaglandins

d.

membrane phospholipid to arachidonic acid

d.

membrane phospholipid to arachidonic acid

What happens when eicosanoids bind to their selective receptors?

a.

G proteins pathways are regulated

b.

All of the above

c.

Calcium-dependent pathways are regulated

d.

Protein kinase pathways are regulated

e.

Adenylate cyclase activities are regulated

b.

All of the above

What is one of the functions of prostacyclin?

a.

Dilation of blood vessel

b.

Synthesis of glucocorticoids

c.

Constriction of blood vessel

d.

Formation of thromboxane

a.

Dilation of blood vessel

What is one of the possible mechanisms by which glucocorticoids regulate inflammation?

a.

via synthesis of triacylglycerides

b.

via inhibition of the phospholipase A2 enzyme

c.

via activation of the inducible form of cyclo-oxygenase type 2 (COX2) enzyme

d.

via activation of the gene expression of the cyclo-oxygenase type 2 (COX2) enzyme

b.

via inhibition of the phospholipase A2 enzyme

What is one of the possible mechanisms by which glucocorticoids regulate inflammation?

a.

Activation of the inducible form of cyclo-oxygenase type 2 (COX2) enzyme

b.

Glucocorticoids binds prostaglandins irreversibly

c.

Inhibition of the secretion of certain chemotactic factors by the inflamed cells

d.

Activation of phospholipase A2 enzyme

c.

Inhibition of the secretion of certain chemotactic factors by the inflamed cells

What is one of the specific structural characteristics of Thromboxane A2 which retains its full functional activities?

a.

Presence of a double bond between Carbon 9 and Carbon 10

b.

Presence of a hydroxyl group attached to the Carbon 15

c.

Absence of a carboxylic acid group

d.

Presence of a saturated five carbon ring

b.

Presence of a hydroxyl group attached to the Carbon 15

What is the mechanism of action of the non-steroidal anti-inflammatory drugs (NSAIDs), ibuprofen and acetaminophen?

a.

They target cyclo-oxygenase and inhibits the enzyme activity by binding irreversibly at the active site of the enzyme so that substrate binding site is blocked

b.

They directly inhibits the lipo-oxygenase pathway

c.

They are reversible competitive inhibitors of the enzyme cyclo-oxygenase

d.

They are irreversible inhibitors of the enzyme cyclo-oxygenase

c.

They are reversible competitive inhibitors of the enzyme cyclo-oxygenase

What is true about eicosanoids?

a.

Eicosanoids are not sensitive to inflammation processes

b.

Eicosanoids are 20 carbon straight chain saturated fatty acids

c.

Eicosanoids are synthesized directly from acetyl-CoA

d.

All eicosanoids are derived from a 20 carbon polyunsaturated fatty acid

d.

All eicosanoids are derived from a 20 carbon polyunsaturated fatty acid

What is TRUE of aspirin?

a.

It is a non-steroidal inflammatory drug

b.

It activates dihydrofolate reductase

c.

It activates prostaglandin biosynthesis

d.

It inhibits cyclooxygenase irreversibly

d.

It inhibits cyclooxygenase irreversibly

What would be the effect of acetylation of the serine hydroxyl group present in the active substrate binding site of the cyclooxygenase enzyme?

a.

It will activate cyclooxygenase enzyme specific activity by 2-fold

b.

This reaction does not influcence the cyclooxygenase enzyme specific activity

c.

It can inhibit thromboxane biosynthesis

d.

This reaction would stimualte prostaglandin biosynthesis

c.

It can inhibit thromboxane biosynthesis

What would be the effect of aspirin during an active inflammatory cascade in human systems?

a.

It would be acetylated

b.

It would decrease the synthesis of archidonic acid

c.

It would inhibit prostaglandin biosynthesis

d.

It would increase thromboxane biosynthesis

c.

It would inhibit prostaglandin biosynthesis

Which compound can synthesize the precursor required for eicosanoid biosynthesis?

a.

Linoleic acid

b.

Glycerol

c.

Palmitic acid

d.

Phosphatidylcholine

a.

Linoleic acid

Which enzyme can release arachidonic acid from membrane phospholipids in order to synthesize prostaglandins?

a.

15-Lipoxygenase

b.

Thromboxane synthase

c.

Cyclooxygenase

d.

Phospholipase A2

d.

Phospholipase A2

Which is one of the crucial function of prostacyclin?

a.

Inhibits platelet aggregation

b.

Stimulates blood clotting cascades

c.

Inhibits thromboxane synthase

d.

Causes vasoconstriction

a.

Inhibits platelet aggregation

Which of the following compounds can activate phospholipase A2 in order to release the precursor molecule for eicosanoid biosynthesis?

a.

Cholesterol

b.

Histamine

c.

Hydroperoxyeicosapentanoic acid

d.

Aspirin

b.

Histamine

Which of the following compounds can release arachidonic acid?

a.

Some membrane bound phospholipids

b.

acetyl-CoA

c.

Thromboxanes

d.

Corticosteroids

a.

Some membrane bound phospholipids

Which of the following compounds could be an activator of phospholipase A2 during eicosanoid biosynthesis?

a.

Histamine

b.

Hydroperoxyeicosapentanoic acid

c.

Aspirin

d.

Cholesterol

a.

Histamine

Which of the following compounds in the eicosanoid biosynthetic pathway synthesizes thromboxane A2?

a.

Prostaglandin H2

b.

Glycine

c.

Leukotriene A4

d.

Prostaglandin I2

a.

Prostaglandin H2

Which of the following compounds is nutritionally essential dietary source of arachidonates in humans?

a.

Palmitate

b.

Linoleate

c.

Eicosapentene

d.

Asparagine

b.

Linoleate

Which of the following compounds is the precursor of eicosanoids?

a.

Glutamic acid

b.

Eicosapentanoic acid

c.

Arachidonic acid

d.

Glycerol

c.

Arachidonic acid

Which of the following drugs is an irreversible inhibitor of the enzyme cyclooxygenase?

a.

Calcitrol

b.

Aspirin

c.

Ibuprofen

d.

Flurouracil

b.

Aspirin

Which of the following eicosanoids activates platelet aggregation?

a.

Hydroperoxyeicosatetraenoic acid

b.

Prostaglandin E1 (PGE1)

c.

Thromboxane A2

d.

Prostacyclin I2 (PGI2)

c.

Thromboxane A2

Which of the following eicosanoids can cause dilation of blood vessels?

a.

Prostaglandin G

b.

Prostacyclin

c.

Thromboxane

d.

Prostaglandin A2

b.

Prostacyclin

Which of the following eicosanoids contains a saturated five carbon ring?

a.

Leukotrienes

b.

Lipoxins

c.

Prostaglandins

d.

Thromboxanes

c.

Prostaglandins

Which of the following eicosanoids inhibits platelet aggregation?

a.

Prostaglandin E1 (PGE1)

b.

Prostaglandin F (PGF)

c.

Prostacyclin (PGI2)

d.

Prostaglandin G2 (PGG2)

c.

Prostacyclin (PGI2)

Which of the following eicosanoids is a powerful vasoconstrictor and also initiates platelet aggregation?

a.

Leukotriene A4

b.

Thromboxane A2

c.

Prostaglandin H2

d.

Lipoxin

b.

Thromboxane A2

Which of the following enzyme system pathways produce lipoxins?

a.

Cytochrome c-oxidase pathway

b.

Enzymes of the pentose phosphate pathway

c.

Lipoxygenase pathway

d.

Cyclooxygenase pathway

c.

Lipoxygenase pathway

Which of the following enzymes catalyzes the formation of prostaglandin H2 from its precursor?

a.

15-Lipo-oxygenase

b.

5-Lipo-oxygenase

c.

Thromoxane synthetase

d.

Cycloxygenase

d.

Cycloxygenase

Which of the following enzymes could be the target for aspirin during eicosanoid biosynthesis?

a.

Thromboxane synthase

b.

Cyclo-oxygenase

c.

Prostacyclin synthase

d.

Lipoxygenase

b.

Cyclo-oxygenase

Which of the following enzymes in the eicosanoid biosynthesis possesses two separate enzyme activities?

a.

Prostacyclin synthase

b.

5-Lipoxygenase

c.

Prostaglandin endoperoxide synthase

d.

15-Lipoxygenase

c.

Prostaglandin endoperoxide synthase

Which of the following enzymes initiates the synthesis of leukotrienes?

a.

12-lipoxygenase

b.

cycloxygenase

c.

5-lipoxygenase

d.

15-lipoxygeanse

e.

epoperoxidase

c.

5-lipoxygenase

Which of the following essential fatty acids is required to synthesize eicosanoids in mammals?

a.

Oleic acid

b.

Stearic acid

c.

Palmitoleic acid

d.

Linoleic acid

d.

Linoleic acid

Which of the following is TRUE?

a.

Eicosanoids binds to their nuclear receptors in order to elicit their action

b.

Eicosanoids binds to their plasma membrane receptors in order to elicit their action

b.

Eicosanoids binds to their plasma membrane receptors in order to elicit their action

Which of the following isoforms of the prostaglandins is the substrate of the enzyme thromboxane A synthase (TXA synthase)?

a.

PGF2

b.

PGG2

c.

PGI2

d.

PGH2

d.

PGH2

Which of the following pathways is involved in the synthesis of leukotrienes?

a.

Cytochrome P450 pathway

b.

Cyclooxygenase pathway

c.

All of the above

d.

Lipoxygenase pathway

d.

Lipoxygenase pathway

Which of the following pathways is involved in the synthesis of lipoxins?

a.

All of the above

b.

Lipoxygenase pathway

c.

Cyclooxygenase pathway

d.

Cytochrome P450 pathway

b.

Lipoxygenase pathway

Which of the following reactions can inactivate thromboxanes?

a.

Addition of an additional peroxide group to thromboxane

b.

All of the above

c.

Reduction of the double bond at Carbon 13

d.

Transamination reaction

c.

Reduction of the double bond at Carbon 13

Which of the following reactions would inactivate thromboxanes?

a.

Addition of serine hydroxyl residue to thromboxane

b.

Transamination reaction

c.

All of the above

d.

Oxidation of the 15-hydroxyl group to a ketone

d.

Oxidation of the 15-hydroxyl group to a ketone

Which of the following sentences is true for glucorticoids?

a.

Glucocorticoids activates phospholipase A2

b.

Glucocorticoids can enhance inducible cyclooxygenase 2 (COX2) activity

c.

Excess secretion of glucocorticoids can decrease arachidonate production

c.

Excess secretion of glucocorticoids can decrease arachidonate production

Which of the following statementns is TRUE of thromboxanes?

a.

It contains a seven membered unsaturated carbon ring

b.

None of the above is correct

c.

It contains six membered ring containing at least one ether linkage

d.

It contains a five member saturated carbon ring

c.

It contains six membered ring containing at least one ether linkage

Which of the following statements is TRUE for eicosanoid biosynthesis?

a.

Dietary glycine can synthesize arachidonic acid

b.

Dietary linoleate can synthesize arachidonic acid

c.

Dietary arginine can synthesize arachidonic acid

d.

Dietary glutamate can synthesize arachidonic acid

b.

Dietary linoleate can synthesize arachidonic acid

Which of the following statements is TRUE?

a.

Eicosanoids are derivatives of isoprene units

b.

Eicosanoids can be produced directly from tryptophan

c.

Eicosanoids can be derived from certain fatty acids

d.

Eicosanoids are obtained from cholesteryl esters

c.

Eicosanoids can be derived from certain fatty acids

Which of the following unsaturated fatty acids is a nutritionally essential dietary source of arachidonates in humans?

a.

Linoleate

b.

Palmitate

c.

Eicosapentene

d.

Asparagine

a.

Linoleate

Which of the following would decrease platelet aggregation, increase cAMP and cause vasodilation?

a.

Prostagladlin I2 (PGI2)

b.

Thromboxane A2

c.

Leukotriene A4

d.

Lipoxins

a.

Prostagladlin I2 (PGI2)

_______________ pathway is involved in the synthesis of leukotrienes?

a.

Cyclooxygenase pathway

b.

Lipoxygenase pathway

c.

Cytochrome P450 pathway

d.

All of the above

b.

Lipoxygenase pathway

________________ inhibits platelet aggregation.

a.

Prostaglandin G2 (PGG2)

b.

Prostaglandin E1 (PGE1)

c.

Prostacyclin (PGI2)

d.

Prostaglandin F (PGF)

c.

Prostacyclin (PGI2)

________________ is an irreversible inhibitor of the enzyme cyclooxygenase.

a.

Flurouracil

b.

Aspirin

c.

Acetaminophen

d.

Ibuprofen

e.

Calcitrol

b.

Aspirin

__________________ is nutritionally essential dietary source of arachidonates in humans.

a.

Eicosapentanate

b.

Palmitate

c.

Linoleate

d.

Asparagine

c.

Linoleate

Topic 6 - Amino Acid Metabolism

A defect in which of the following enzymes can result in alcaptonuria?

a.

Tyrosine hydroxylase

b.

Phenylalanine hydroxylase

c.

Homogentisate oxidase

d.

Glycine transaminase

c.

Homogentisate oxidase

Alkaptonuria is a disease of __________________

a.

defective glycine metabolism

b.

defective branched chain amino acid metabolism

c.

defective phenylalanine metabolism

d.

defective homocysteine metabolism

c.

defective phenylalanine metabolism

Catabolism of which of the following types of amino acid produces acetoacetyl-CoA?

a.

Purinergic

b.

Glucogenic

c.

Ketogenic

d.

Aminergic

c.

Ketogenic

Defective activity of which of the following enzymes is responsible for Maple Syrup Urine disease?

a.

Phenylalanine hydroxylase

b.

Cystathione beta-synthase

c.

Glycine transaminase

d.

Branched chain alpha-keto acid dehydrogenase

d.

Branched chain alpha-keto acid dehydrogenase

Defective metabolism of branched chain amino acids would lead to:

a.

Maple syrup urine disease

b.

Phelylketonuria

c.

Homocyteinuria

d.

Alkaptonuria

a.

Maple syrup urine disease

Erythrose 4-phosphate is one of the precursors to which amino acids:

a.

tryptophan, tyrosine and phenylalanine

b.

tryptophan, arginine and serine

c.

tyrosine, valine and glutamate

d.

alanine, histidine and glycine

a.

tryptophan, tyrosine and phenylalanine

If a person's urine contains unusually high concentrations of urea, which one of the following diets has he or she probably been eating recently?

a.

Very high carbohydrate, no protein, no fat

b.

High carbohydrate, very low protein

c.

Very, very high fat, high carbohydrate, no protein

d.

Very high fat, very low protein

e.

Very low carbohydrate, very high protein

e.

Very low carbohydrate, very high protein

If an amino acid is catabolized to produce acetoacetyl-CoA, it is said to be _____.

a.

Aminergic

b.

Ketogenic

c.

Purinergic

d.

Glucogenic

b.

Ketogenic

In a recent COVID-19 pandemic outbreak some patients admitted to the hospitals have shown low oxygen levels in blood.

An instantaneous in vivo biosynthesis of a cytosolic gaseous product has been shown to improve blood flow in the areas of lungs still receiving air and thereby, increase amount of oxygen flow in the blood stream.

Which of the following amino acids can produce this compound as well functions as a gaseous neurotransmitter?

a.

arginine

b.

tyrosine

c.

glutamate

d.

histidine

d.

histidine

In a single-step transamination reaction using alpha-ketoglutarate as one of the reactants, alanine would produce:

a.

cysteine and pyruvate

b.

pyruvate and glutamate

c.

glutamine and glutamate

d.

alpha-ketoglutarate and glycine

b.

pyruvate and glutamate

In the treatment of diabetes, insulin is given intravenously. Why can't this hormone, a small protein, be taken orally?

a.

low stomach pH and intestinal protease activity may denature and degrade insulin respectively.

b.

amino acids present in insulin will undergo transamination reactions.

c.

Oral insulin administration will increase blood glucose levels.

d.

alpha-ketoglutarate present in the intestine cannot exchange its alpha-keto group with the amino groups present in insulin.

a.

low stomach pH and intestinal protease activity may denature and degrade insulin respectively.

John's diet is very rich in proteins, and very low in carbohydrates. Concentration of which of the following compounds will be very high in his urine?

a.

Sodium ion

b.

Acetyl-CoA

c.

Urea

d.

Peptides

c.

Urea

[MACA] The disease phenylketonuria is characterized by which of the following?

a.

High serum levels of phenylalanine

b.

High levels of phenylketone in urine

c.

Accumulation of phenylpyruvate

d.

Phenylalanine is not hydroxylated

All Are Correct

a.

High serum levels of phenylalanine

b.

High levels of phenylketone in urine

c.

Accumulation of phenylpyruvate

d.

Phenylalanine is not hydroxylated

Oxidative deamination of which of the following compounds directly produces ammonium ions (NH4+)?

a.

Glutamate

b.

alpha-Ketoglutarate

c.

Tetrahydrofolate

d.

Proline

a.

Glutamate

Primary oxaluria type I is caused by defective metabolism of:

a.

phenylalanine

b.

glycine

c.

alanine

d.

branched chain amino acids

b.

glycine

Ring hydroxylation of which of the following essential amino acids produces tyrosine?

a.

Phenylalanine

b.

Histidine

c.

Arginine

d.

Threonine

d.

Threonine

Surplus amino acids are:

a.

all of the above

b.

stored in proteasomes

c.

used as metabolic fuel

d.

stored in liver

c.

used as metabolic fuel

The amino acids serine, alanine, and cysteine can be catabolized to yield:

a.

alpha-ketoglutarate

b.

succinate

c.

fumarate

d.

pyruvate

d.

pyruvate

Tetrahydrobiopterin can participate in:

a.

the formation of tetrahydrofolate

b.

methylation of vitamin B12

c.

aromatic ring decarboxylation

d.

aromatic amino acid ring hydroxylation

d.

aromatic amino acid ring hydroxylation

The disease phenylketonuria is characterized by which of the following?

a.

All of the above

b.

High serum levels of phenylalanine

c.

Accumulation of phenylpyruvate

d.

Phenylalanine is not hydroxylated

e.

High levels of phenylketone in urine

d.

Phenylalanine is not hydroxylated

The genetic defect of which of the following enzymes causes phenylketonuria?

a.

serine hydratase

b.

homogentisate oxidase

c.

phenylalanine hydroxylase

d.

tyrosine hydroxylase

c.

phenylalanine hydroxylase

The genetic defect of which of the following enzymes causes phenylketonuria?

a.

tyrosine hydroxylase

b.

phenylalanine hydroxylase

c.

serine hydratase

d.

homogentisate oxidase

b.

phenylalanine hydroxylase

What is the function of glutaminase?

a.

It synthesizes alanine

b.

It is responsible for one-carbon group transfer

c.

It produces glutamine

d.

It produces glutamate

d.

It produces glutamate

What is the major cause of the disease Maple syrup urine?

a.

It is caused by S-adenosylmethionine (SAM) deficiency

b.

It is caused by defective metabolism of branched chain amino acids

c.

It is caused by defective catabolism of phenylalanine

d.

It is caused by defective homocysteine metabolism

b.

It is caused by defective metabolism of branched chain amino acids

What is the product of enzyme catalyzed breakdown of glutamic acid?

a.

Glucose

b.

Pyruvic acid

c.

Citric acid

d.

α-Ketoglutarate

d.

α-Ketoglutarate

What is TRUE of Kwashiorkor?

a.

It is caused by excess dietary proteins

b.

It is a disease in which fatty acids are oxidized

c.

It can produce negative nitrogen balance in humans

d.

It is not caused by diets deficient in proteins

c.

It can produce negative nitrogen balance in humans

Which amino acid is produced in a transamination reaction when α-ketoglutarate reacts with another amino acid, such as glutamine?

a.

Arginine

b.

Glutamate

c.

Isoleucine

d.

Alanine

b.

Glutamate

Which amino acid is the immediate precursor of methionine?

a.

Homocysteine

b.

Glycine

c.

Histidine

d.

Serine

a.

Homocysteine

Which amino acid is the immediate precursor of tyrosine?

a.

Phenylalanine

b.

Alanine

c.

Glutamate

d.

Cysteine

a.

Phenylalanine

Which enzyme catalyzes the conversion of glutamine to glutamate?

a.

Glutamine synthetase

b.

Glutamate dehydrogenase

c.

Alanine aminotransferase

d.

Glutaminase

d.

Glutaminase

Which of the following amino acid is nutritionally essential in humans?

a.

tryptophan

b.

glutamate

c.

alanine

d.

aspartate

a.

tryptophan

Which of the following amino acids is glucogenic?

a.

Lysine

b.

Glutamic acid

c.

Leucine

b.

Glutamic acid

Which of the following amino acids is NOT derived from glycolysis?

a.

Glycine

b.

Alanine

c.

Arginine

d.

Serine

c.

Arginine

Which of the following amino acids is strictly ketogenic and produces acetyl-CoA?

a.

Glycine

b.

Leucine

c.

Serine

d.

Alanine

b.

Leucine

Which of the following amino acids is the precursor for the skin pigment melanin?

a.

Tryptophan

b.

Glycine

c.

Tyrosine

d.

Alanine

c.

Tyrosine

Which of the following amino acids is strictly ketogenic?

a.

Alanine

b.

Lysine

c.

Serine

d.

Glycine

b.

Lysine

Which of the following amino acids is the precursor to dopamine?

a.

Tryptophan

b.

Valine

c.

Tyrosine

d.

Alanine

c.

Tyrosine

Which of the following amino acids is the precursor of melatonin?

a.

Tryptophan

b.

Tyrosine

c.

Phenylalanine

d.

Glutamate

a.

Tryptophan

Which of the following amino acids is used to synthesize cysteine?

a.

serine

b.

alanine

c.

phenylalanine

d.

proline

a.

serine

Which of the following amino acids is used to synthesize glycine?

a.

Serine

b.

Histidine

c.

Phenylalanine

d.

Tyrosine

a.

Serine

Which of the following can donate the sulfhydryl group (-SH) for cysteine biosynthesis?

a.

Alanine

b.

Glutamic acid

c.

Glycine

d.

Homocysteine

d.

Homocysteine