20. The biosynthesis of tyrosine in normal humans requires which of…

Question Answered step-by-step 20. The biosynthesis of tyrosine in normal humans requires which of… 20. The biosynthesis of tyrosine in normal humans requires which of the following amino acids in the diet?A. phenylalanineB. methionineC. histidineD. threonineE. leucine   21.Turnover number (Kcat)A. is a ratio of the rate constants for the formation of ES and of productB. has units of substrate concentrationC. is inversely related to how fast the reaction isD. has units of 1/time   22. Which of the following ligand has the greatest affinity for the enzyme?A: Ligand with a Km value of 0.020 ˩MB: Ligand with a Km value of 0.009 mMC: Ligand with a Km value of 100 nMD: Ligand with a Km value of 0.00006 MX E: Ligand with a Km value of 100 ˩M   23. Proteins in membranesA. are located only at the external surface of the membrane.B. have carboxy termini is usually oriented toward the exterior part of the cell.C. consist of a small number of low molecular weight proteins.D. are located both on the surface and in the interior of the membrane.E. are located only in the internal portion of the membrane.   24. To what superfamily of transporters do the P-glycoproteins belong?A. ABC (ATP-binding cassette)B. Calmodulin-associatedC. GlyceroaquaporinsD. IonophoresE. Secondary active    25. In the study of biological membranes, detergents are used toA. alter the weak acid properties of membrane components.B. covalently modify specific amino acid residues in proteins.C. disrupt interactions between lipids and proteins.D. enhance associations between integral and peripheral proteins.E. replace a lipid anchor on a protein with a detergent molecule.   26. To what superfamily of transporters do the P-glycoproteins belong?A. ABC (ATP-binding cassette)B. Calmodulin-associatedC. GlyceroaquaporinsD. IonophoresE. Secondary active   27. Why does a polymorphism in CYP2D6 decrease the efficacy of codeine?A. Alters the number of AhRB. Decreases uptake of codeine by the brainC. Increases excretion of codeineD. Increases Phase II metabolismE. Slows formation of morphine  28. What is the most common enzyme deficiency in adrenal hyperplasia?A. CYP11A1 (scc)B. CYP21A2C. CYP24A1D. CYP3A4E. CYP7A1  29. The absorption maximum at 450 nm of cytochrome P450 requires that the iron be in the Fe++ state and bound to a specific molecule. What is this molecule?A. COB. CO2C. H2OD. NADPHE . O2     30. What is the prosthetic group of cytochrome P450?A. FlavinB. HemeC. Iron-sulfurD. Pyridine nucleotideE. Thiamine   31. Why did administration of erythromycin make the use of Terfenadine in a patient contraindicated?A. Erythromycin accelerates excretion of SeldaneB. Erythromycin binds to a product of Seldane metabolismC. Erythromycin caused Phase II metabolism of SeldaneD. Erythromycin induces metabolism of SeldaneE. Erythromycin inhibits metabolism of Seldane   32. The protein cytochrome P450 found in liver microsomesA. is reduced by NADPH directly without a reductase enzyme.B. binds hydroxylatable substrates and oxygen.C. requires catalytic amounts of a non-heme iron protein called ferritin.D. converts lipophilic compounds into conjugates with sulfate or glucuronic acid.E. All of the above.   33. Which class of hormones are synthesized by a series of cytochrome P450s?A. Amino acid derivativesB. CytokinesC. PeptidesD. SteroidE. Thyroid   34. The liver microsomal monooxygenase system containing cytochrome P450 can modify drugs byA. formation of a sulfate group.B. addition of an acyl residue.C. formation of an hydroxyl group.D. addition of a glucuronic acid residue.E. formation of a disulfide bond.   35. The biotransformation reactions of detoxication occur primarily inA. liver.B. kidney.C. muscle.D. brain.E. uterus.   36. In the cytochrome P450 cycle, what binds first?A. An electron on oxygenB. An electron on the iron atomC. OxygenD. SubstrateE. Water   37. Premature infants may exhibit the respiratory distress syndrome due to inadequate secretion ofA. sphingomyelinB. dioleoyl phosphatidyl inositol.C. dipalmitoleoyl phosphatidylcholineD. cholesterol.E. dipalmitoyl phosphatidyl choline.   38. PCR is used for all of the following EXCEPTA. quantification of DNA synthesized.B. amplification of a target DNA sequence.C. in vivo correction of a mutated gene.D. detection of single nucleotide changes.   39. A technique that is used to determine the particular mRNA isA. gel shift assay.B. Southern blotting.C. DNA ligation.D. Northern blotting.   40. Transgenic mouse lines are useful for studies of human disease for all the following reasons EXCEPTA. Mice are physiologically similar to humans.B. New diseases can be induced in mice for which there is no human counterpart yet.C. They allow the study of polygenic disease.D. Technology advances have increased the ability to create mouse models of human disease.E. A large reservoir of potential models exists in spontaneous or induced mutant loci.    ______________________________________     Biology Science Biochemistry TERM 230 Share QuestionEmailCopy link Comments (0)