Biochem
Lactate dehydrogenase belongs to which group of enzymes? a. hydrolases c. oxidoreductases b. lyases d. transferases
C
Which of the following is true of all allosteric enzymes? a. They consist of proteins only. b. They have a nonprotein portion. c. They have more than one active site on each subunit. d. Binding at one site affects protein function at a second site.
D
Which of the following is true of trypsin? a. It does not affect any peptide bonds. b. It hydrolyzes all peptide bonds. c. It hydrolyzes peptide bonds to leucine and phenylalanine. d. It hydrolyzes peptide bonds to arginine and lysine.
D
Which of the following is true? a. All enzymes are fibrous proteins. b. All enzymes are globular proteins. c. The majority of enzymes are fibrous proteins. d. The majority of enzymes are globular proteins.
D
Aconitase belongs to which group of enzymes? a. hydrolases c. oxidoreductases b. lyases d. transferases
B
An abzyme is which of the following? a. an abnormal enzyme c. an antigen with catalytic ability b. an antibody with catalytic ability d. an immunogen
B
Enzymes are classified into how many different major groups? a. 4 c. 8 b. 6 d. 10
B
In which type of inhibition does the inhibitor bind to the active site? a. cooperative inhibition c. noncompetitive inhibition b. competitive inhibition d. selective inhibition
B
In which type of inhibition is it possible to restore the maximum rate of enzyme activity by adding additional substrate? a. cooperative inhibition c. noncompetitive inhibition b. competitive inhibition d. selective inhibition
B
The names of enzymes are often derived from which of the following? a. the name of their discoverer c. both a and b b. the compound on which they act d. neither a nor b
B
Tyrosine-tRNA synthetase belongs to which group of enzymes? a. hydrolases c. oxidoreductases b. ligases d. transferases
B
What is the name given to a material which slows down enzyme function? a. closer c. isozyme b. inhibitor d. substrate
B
Which of the following can cause enzyme activity to either increase or decrease? a. increasing the substrate concentration b. changing the pH c. both a and b d. neither a nor b
B
Which of the following is catalyzed by arginase? a. the conversion of D-arginine to urea and D-ornithine b. the conversion of L-arginine to urea and L-ornithine c. the conversion of L-arginine to urea and D-arginine d. the conversion of both the D and L forms of arginine to urea and the D and L forms of ornithine
B
Which of the following is true of enzymes? a. They shift the position of a chemical equilibrium. b. They speed up the rate of a chemical reaction. c. both a and b d. neither a nor b
B
Which of the following is true? a. Both competitive and noncompetitive inhibition are never reversible. b. Both competitive and noncompetitive inhibition are sometimes reversible. c. Only competitive inhibition is sometimes reversible. d. Only noncompetitive inhibition is sometimes reversible.
B
Which of the following will the cause the rate of enzyme activity to first increase and then level off? a. increasing the enzyme concentration b. increasing the substrate concentration c. increasing the temperature d. increasing the pH
B
What designations are used to distinguish between the two forms of an allosteric enzyme? a. alpha and beta c. R and S b. D and L d. R and T
D
What disease is diagnosed by monitoring acid phosphatase activity? a. hepatitis c. pancreatic disease b. liver cancer d. prostate cancer
D
What term is used to describe a species which affects the functioning of an allosteric enzyme? a. alloster c. inhibitor b. controller d. regulator
D
Which of the following are monitored to diagnose the severity of a heart attack? a. AST c. LDH b. CPK d. all of these
D
Which of the following explains why succinylcholine is used as a muscle relaxant? a. It destroys acetylcholine esterase. b. It is not hydrolyzed by acetylcholinesterase. c. It is rapidly hydrolyzed by acetylcholinesterase. d. It is slowly hydrolyzed by acetylcholinesterase.
D
Which of the following is another name for a proenzyme? a. allosteric enzyme c. cofactor b. coenzyme d. zymogen
D
Acetylcholinesterase belongs to which group of enzymes? a. hydrolases c. oxidoreductases b. lyases d. transferases
A
Noncompetitive inhibition can be often explained by which of the following models? a. the induced fit model c. both a and b b. the lock and key model d. neither a nor b
A
Which of the following can cause enzyme activity to either increase or decrease? a. changing the temperature b. increasing the substrate concentration c. both a and b d. neither a nor b
A
Which of the following is associated with noncompetitive inhibition? a. allosterism c. isomerization b. allotropism d. racemization
A
Which of the following is used in diagnosing infectious hepatitis? a. ALT c. LDH b. CPK d. PHI
A
Which of the following will cause the rate of enzyme activity to increase linearly? a. increasing the enzyme concentration b. increasing the substrate concentration c. increasing the temperature d. increasing the pH
A
Which types of amino acids interact most strongly with metal ions? a. those with acidic side chains c. those with nonpolar side chains b. those with basic side chains d. those with polar side chains
A
Competitive inhibition can be explained by which of the following models? a. the induced fit model c. both a and b b. the lock and key model d. neither a nor b
C
In which type of inhibition does the inhibitor bind to the protein at a site other than the active site? a. cooperative inhibition c. noncompetitive inhibition b. competitive inhibition d. selective inhibition
C
In which type of inhibition is it not possible to restore the maximum rate of enzyme activity by adding additional substrate? a. cooperative inhibition c. noncompetitive inhibition b. competitive inhibition d. selective inhibition
C
The names of enzymes are often derived from which of the following? a. the reaction they catalyze c. both a and b b. the compound on which they act d. neither a nor b
C
What disease is diagnosed by monitoring amylase activity? a. hepatitis c. pancreatic disease b. liver cancer d. prostate cancer
C
What is an apoenzyme? a. an enzyme made entirely of protein c. the protein only part of an enzyme b. the nonprotein part of an enzyme d. the inactive form of an enzyme
C
What is the general name used when the product of a reaction sequence inhibits an earlier step in that sequence? a. cooperative inhibition c. feedback control b. competitive inhibition d. stereospecificity
C
What name is given to any (organic or inorganic) nonprotein portion of an enzyme?a. apoenzyme c. cofactorb. coenzyme d. substrate
C
What name is given to the intermediate in an enzyme-catalyzed reaction? a. apoenzyme c. enzyme-substrate complete b. coenzyme d. zymogen
C
What name is given to the molecule on which the enzyme works? a. cofactor c. substrate b. isozyme d. zymogen
C
What name is given to the organic cofactor of an enzyme? a. apoenzyme c. coenzyme b. chaperone d. substrate
C
Which of following is true of urease? a. It catalyzes the degradation of uracil. b. It catalyzes the synthesis of urea. c. It catalyzes the hydrolysis of urea. d. It catalyzes the hydrolysis of all amines
C
Which of the following can cause enzyme activity to either increase or decrease? a. changing the temperature c. both a and b b. changing the pH d. neither a nor b
C
Which of the following is a foreign substance that produces an immune response? a. an abzyme c. an antigen b. an antibody d. none of these
C
Which of the following is commonly associated with protein modification? a. phosphorylation c. both a and b b. dephosphorylation d. neither a nor b
C
Which of the following is often true of the active site of an enzyme? a. It consists of amino acids near both the N-terminus and C-terminus. b. It consists of amino acids which are adjacent to each other. c. It consists of amino acids which not adjacent to each other. d. None of the above is true.
C
Which of the following is the reason that trypsin is synthesized as trypsinogen? a. It is simpler to synthesize trypsinogen. b. Trypsinogen is a more active enzyme than trypsin. c. Trypsin would attack the body's natural proteins. d. Trypsin is a larger molecule than trypsinogen.
C
Which of the following is true of enzymes? a. They lower the activation energy for a chemical reaction. b. They speed up the rate of a chemical reaction. c. both a and b d. neither a nor b
C
Which of the following is true of isozymes? a. Their amino acid sequences are mirror images of one another. b. They are a pair of enzymes which must both be present for enzyme activity to occur. c. They are different forms of the same enzyme found in different tissues. d. None of the above is true.
C
Transition-state analogs do which of the following? a. They help chemists verify the nature of the active site b. They inhibit enzyme activity. c. They offer the possibility of creating designer enzymes. d. All of the above are correct.
D
Aspartate transaminase belongs to which group of enzymes? a. hydrolases c. oxidoreductases b. lyases d. transferases
D
In addition to proteins, which type of molecules sometimes function as enzymes? a. carbohydrates c. lipids b. DNA d. RNA
D
Transition-state analogs do which of the following? a. They assist in the synthesis of specialized enzymes. b. They assist in transporting the substrate to the active site. c. They enhance enzyme activity. d. They inhibit enzyme activity.
D