Q bank II Flashcards by ROSCIAE SAVIOR

Which of the following tissues or organs plays a significant role in gluconeogenesis after 4 days of fasting but not after and overnight fasting?

Kidney. If its for overnight, then its the liver

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All of the following tissues can use circulating fatty acids as metabolic fuel except:

Brain

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Analysis of a patient’s serum showed elevated VLDL. Which of the following mechanisms accounts in part for this process?

decreased activity of lipoprotein lipase

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The isozyme form of creatine kinase in skeletal muscle is

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Which one of the following glucose transporters are regulated by insulin?

GLUT 4

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Most sphingolipidoses results from genetic deficiencies of which one of the following enzymes

glycosidases

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The conversion of Propionyl-Coa to succinyl-Coa requires

biotin and vitamin B12

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The release of arachidonate by phospholipase A2 from membrane phospholipids is inhibited by

lipocortin

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The two nitrogen atoms in urea arise from

ammonia and aspartic acid

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The normal brown red color of feces results from the presence of

Stercobilin

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The most common drug-induced hemolytic anemia is found in patients who are deficient in which of the following enzymes

Glucose-6-phosphate dehydrogenase

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Patients with a antiproteinase deficiency may develop emphysema because they cannot.

block the action of leukocyte elastase released by activated neutrophils in the lung

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Marfan syndrome is associated with a defect in the structure of

Elastin

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All of the cells are stimulated by epinephrine except

Glucose Oxidation

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The inhibition of the DNA synthesis by methotrexate results from direct inhibition of

The reduction of dihydrofolate to tetrahydrofolate

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A liver biopsy from an infant with a large liver and kidney, hypoglycemia acidosis and hyperlipidemia revealed a massive buildup of glycogen with a normal structure. A possible diagnosis would be.

Glucose-6-phosphatase deficiency (von Gierke’s disease)

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Which of the following compounds are the most ketogenic?

amino acids that are degraded to Acetyl-CoA

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McArdle disease is a myopathy that results in an ability to perform anaerobic exercise. the disease is due to a deficiency of the enzyme that catalyzes the predominant reaction of glycogenolysis and this enzyme involves which one of the following processes?

phosphorolysis reaction

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The extracellular 1st messenger that initiates the cAMP dependent glycogenolytic cascade in muscle is

Epinephrine

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Increased formation of ketone bodies during starvation is due to

increased levels of free fatty acids in serum

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A lack of insulin in humans would result in which one of the following reactions in the liver?

increased formation of 3-hydroxybutyrate

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Sulfa drugs interfere with the bacterial synthesis of

Folic Acid

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What is true statement about Niemann-Pick disease

it is due to a deficiency of the enzyme that hydrolytically removes phosphorylcholine from spingomyelin

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The primary biochemical lesion in patients with familial hypercholesterolemia is:

The functional deficiency of plasma membrane receptors for low-density lipoproteins

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Which one of the following is correct regarding the well fed state?

The major source of fuel for the brain is glucose

All of the following vitamins give rise to cofactors that are phosphorylated in the active form exept

riboflavin

Most major metabolic pathways are considered to be either mainly anabolic or catabolic. Which of the following pathways is most correctly considered to be amphibolic?

Citric Acid Cycle

Insulin regulates fatty acid synthesis by

dephosphorylating of acetyl-Coa carboxylase

Respiratory distress syndrome in premature infants is due to inadequate secretion of which one of the following lipids?

phosphatidylcholine

A cyclooxygenase is required for the production of

thromboxanes from arachidonic acid

The symptom of the dietary deficiency of of niacin (which results in pellagra) will be less severe if the diet has a high content of

Tryptophan

Each of the following vitamins is required for the reactions in the oxidation of pyruvate to CO2 and H2O EXCEPT:

Biotin

The major process responsible for maintaining blood glucose 4 hours after the last meal is:

glycogenolysis

The major process responsible for maintaining blood glucose 40 hours after the last meal is

gluconeogenesis

In an individual at rest who has fasted for 12 hours:

phosphorylase, pyruvate kinase and glycogen synthetase are phosphorylated in liver

Administration of a high dose of glycogen to this patient 2-3 hours after a high carbohydrate meal:

would have little effect on blood glucose level

. Which one of the following sequences places the lipoprotein in the order of most dense to least dense?

HDL/ LDL/VLDL/chylomicron

Which one of the following occurs in the conversion of fatty acids to ketone bodies?

Acetoacetate and acetyl CoA are produced y cleavage of HMG CoA*

Pyridoxial phosphate is required for the enzymes catalyzing the reaction

pyruvate + glutamate –> alanine + alpha ketoglutarate

In the human, prostaglandin can be derived from:

.arachidonic acid

Which of the following metabolites is the stoichiometric substrate of the Kreb Cycle?

Acetyl CoA

Malic enzyme performs all the following functions EXCEPT

catalyzing the gernation of malate from pyruvate

Pyruvate dehydrogenase phosphatase deficiency in humans has which of the following effects:

it leads to lactic acidemia*

. Which of the following is a true statement regarding cytosolic carbamoyl-phosphate synthetase II in humans?

it is one of the 3 activities residing in a single polypeptide called CAD complex*

5-Phosphoribosyl 1 pyrophosphate (PRPP) is an intermediate in all the following pathways EXCEPT:

the pentose phosphate pathway

Thymidylate synthase, an enzyme whose activity is high in rapidly dividing tumor cells, performs all the following function EXCEPT:

providing pyrimidine nucleotides for mRNA synthesis

The mechanism of action of glucagon involves all of the following steps EXCEPT

activation protein kinase C

the enzyme in the heme biosynthetic pathway that is most sensitive to lead is

Aminolevulinic acid (ALA) dehydratase

The rate limiting reaction in protoporphyrin IX synthesis is catalyzed by

Aminolevulinic acid (ALA) synthase

The first step in heme catabolism

heme oxygenase

The rate limiting step in urea cycle is

carbamoyl phosphate synthetase I

Which one of the following amino acids is catabolized preferentially by the liver when compared with skeletal muscle?

alanine

The elevated blood glucose seen in diabetes melliatus is a consequence of: failure of glucose to enter liver cells

increased activity of gluconeogenic enzymes due to enzyme induction by glucagon

Which one of the following enzymes is rate limiting for de novo purine nucleotide synthesis and is thus a target for drugs used in treatment in gout?

phosphoribosylpyrophosphate-glutamine amidotransferase (PRPP amidotransferase

The elevation of blood ketone bodies results from deficiency of the enzyme:

Succinyl CoA-acetoacetate CoA-transferase

What is the first purine nucleotide formed during de novo synthesis

inosine monophosphate

The administration of L-dopa which is given in the treatment of Parkinson’s disease bypass the rate limiting enzyme of catecholamine biosynthesis. What is the name of the enzyme?

tyrosine hydroxylase

Dermatan and heparan sulfates accumulate in Hurler’s syndrome

alpha-L iduronidase | 3'phosphoadenosine 5' phosphosulfate (PAPS)

Which of the following is true concerning transketolase?

It utilizes TPP as cofactor in catalyzing the transfer of two carbon fragment from one sugar phosphate to another

Dinitrophenol uncouples oxidation and phosphorylation in which one of the following ways?

By dissipating the proton gradient between the mito matrix and the intermembrane space

Aspirin is an irreversible inhibitor of:

cyclooxygenase

All of the following are true statements regarding glutamine PRPP amidotransferase EXCEPT

it is activated by IMP

Which AA binds to zinc of zinc finger proteins?

cysteine and histidine

Which of the following compounds is not an allosteric regulator of PFK activity?

F6P

A deficiency of any of the following AA leads to negative nitrogen balance in humans EXCEPT

ornithine

The rate limiting reaction in prostaglandin biosynthesis:

phospholipase A2

Which enzyme requires TPP as a cofactor in pentose phosphate pathway?

transketolase

The enzyme that catalyzes an anaplerotic reaction in the citric acid cycle is:

pyruvate carboxylase

Which one of the following statement about the major collagen type from skin or bone is correct

The procollagen molecule contains non helical C- and N- terminal extensions

The congenital deficiency of a1-antitrypsin is associated with susceptibility of

emphysema

Chronic or long term regulation of enzymatic activity as opposed to acute changes in enzymatic activity ,is best affected by which of the following regulatory controls?

synthesis or degradation of enzyme