What is the limiting substance in the biosynthesis of purines?
A. ribose-5-phosphate
B. 5-phosphoribosyl-β amine
C. formyl glycin amidine ribonucleotide
D. 5-phosphoribosyl-α-pyrophosphate (PRPP)
E. α-D-ribose-5-phosphate - ANSWER D
The coenzyme for two single carbon additions in purine biosynthesis is:
A. THF
B. biotin
C. SAM
D. TPP
E. none are true - ANSWER A
What is the common product of purine catabolism?
A. xanthine
B. uric acid
C. inosine
D. hypoxanthine
E. xanthosine - ANSWER B
Thymidylate synthase synthesizes dTMP from __ by __ , utilizing the coenzyme
__.
A. dCTP; carboxylation; biotin
B. dUMP; methylation; THF
C. dCMP; methylation; THF
D. dGMP; phosphorylation; ATP
E. dUMP; phosphorylation; ATP - ANSWER B
Which is a six-membered heterocyclic aromatic ring?
A. pyrimidine
B. purine
,C. anose
D. sugar portion of DNA
E. ribonucleotide - ANSWER A
Which of the following statements regarding the structure of DNA is correct?
A. the two strands are parallel
B. the two strands are held together by intrachain hydrogen bonds
C. the two strands have complementary base pairing
D. the ;hydrogen bonding that holds the helix together is always between two
purines or between two pyrimidines
E. the ratio of adenine to guanine is the same in all organisms - ANSWER C
The convention in all notations of nucleic acid structure is to read the
polynucleotide chain from the __ of the polymer to the __.
A. poly U head; poly A tail
B. 3' end; 5' tail
C. 5' end; 3' end
D. poly-p head; 5' head
E. none are true - ANSWER C
In eukaryotic cells, a class of __- and __-rich proteins called __ interact
ionically with the anionic phosphate groups in the DNA backbone to form __.
A. lysine; leucine; prions; ribosomes
B. arginine; lysine; histones; nucleosomes
C. arginine; alanine; histones; nucleosomes
D. arginine; lysine; prions; ribosomes
E. none are true - ANSWER B
Eukaryotic mRNAs are synthesized in the nucleus, are called __, and contain
noncoding regions called __ because they intervene between coding regions
called __.
A. poly A RNAs; noncodons; codons
B. poly A RNAs; intervening sequences; codons
C. heterogeneous nuclear RNAs; intervening sequences (introns); codons
D. heterogeneous nuclear RNAs; intervening sequenes (introns); exons
E. none of the above - ANSWER D
Enzymes that catalyze the unwinding of DNA double helices are:
, A. topoisomerases
B. helicases
C. ligases
D. gyrases
E. polymerases - ANSWER B
SSBs are:
A. substrates for DNA ligases
B. supercoil stabilizing bodies
C. single-stranded bodies called Okazaki fragments
D. single-stranded DNA binding proteins that prevent re-annealing
E. nucleases that hydrolyze single-stranded RNA primers - ANSWER D
Which of the following is NOT true regarding E. coli replication on the lagging
strand?
A. primarily carried out by DNA polymerase I
B. synthesized discontinuously
C. performed in a 5' 3' direction of synthesis
D. initially synthesized as Okazaki fragments
E. requires the enzymes primase and DNA ligase - ANSWER A
DNA polymerases share all of the following characteristics EXCEPT:
A. incoming bases are paired with corresponding bases on the template strand
within the polymerase active site
B. polymerization proceeds in a 5' 3' direction
C. polymerization is antiparallel to template strand
D. strong processivity
E. polymerization is dependent upon the presence of an oligonucleotide primer -
ANSWER D
The enzyme that removes the RNA primer from the Okazaki fragment is:
A. DNA polymerase I
B. DNA ligase
C. helicase
D. DNA polymerase III
E. DNA gyrase - ANSWER A
A. ribose-5-phosphate
B. 5-phosphoribosyl-β amine
C. formyl glycin amidine ribonucleotide
D. 5-phosphoribosyl-α-pyrophosphate (PRPP)
E. α-D-ribose-5-phosphate - ANSWER D
The coenzyme for two single carbon additions in purine biosynthesis is:
A. THF
B. biotin
C. SAM
D. TPP
E. none are true - ANSWER A
What is the common product of purine catabolism?
A. xanthine
B. uric acid
C. inosine
D. hypoxanthine
E. xanthosine - ANSWER B
Thymidylate synthase synthesizes dTMP from __ by __ , utilizing the coenzyme
__.
A. dCTP; carboxylation; biotin
B. dUMP; methylation; THF
C. dCMP; methylation; THF
D. dGMP; phosphorylation; ATP
E. dUMP; phosphorylation; ATP - ANSWER B
Which is a six-membered heterocyclic aromatic ring?
A. pyrimidine
B. purine
,C. anose
D. sugar portion of DNA
E. ribonucleotide - ANSWER A
Which of the following statements regarding the structure of DNA is correct?
A. the two strands are parallel
B. the two strands are held together by intrachain hydrogen bonds
C. the two strands have complementary base pairing
D. the ;hydrogen bonding that holds the helix together is always between two
purines or between two pyrimidines
E. the ratio of adenine to guanine is the same in all organisms - ANSWER C
The convention in all notations of nucleic acid structure is to read the
polynucleotide chain from the __ of the polymer to the __.
A. poly U head; poly A tail
B. 3' end; 5' tail
C. 5' end; 3' end
D. poly-p head; 5' head
E. none are true - ANSWER C
In eukaryotic cells, a class of __- and __-rich proteins called __ interact
ionically with the anionic phosphate groups in the DNA backbone to form __.
A. lysine; leucine; prions; ribosomes
B. arginine; lysine; histones; nucleosomes
C. arginine; alanine; histones; nucleosomes
D. arginine; lysine; prions; ribosomes
E. none are true - ANSWER B
Eukaryotic mRNAs are synthesized in the nucleus, are called __, and contain
noncoding regions called __ because they intervene between coding regions
called __.
A. poly A RNAs; noncodons; codons
B. poly A RNAs; intervening sequences; codons
C. heterogeneous nuclear RNAs; intervening sequences (introns); codons
D. heterogeneous nuclear RNAs; intervening sequenes (introns); exons
E. none of the above - ANSWER D
Enzymes that catalyze the unwinding of DNA double helices are:
, A. topoisomerases
B. helicases
C. ligases
D. gyrases
E. polymerases - ANSWER B
SSBs are:
A. substrates for DNA ligases
B. supercoil stabilizing bodies
C. single-stranded bodies called Okazaki fragments
D. single-stranded DNA binding proteins that prevent re-annealing
E. nucleases that hydrolyze single-stranded RNA primers - ANSWER D
Which of the following is NOT true regarding E. coli replication on the lagging
strand?
A. primarily carried out by DNA polymerase I
B. synthesized discontinuously
C. performed in a 5' 3' direction of synthesis
D. initially synthesized as Okazaki fragments
E. requires the enzymes primase and DNA ligase - ANSWER A
DNA polymerases share all of the following characteristics EXCEPT:
A. incoming bases are paired with corresponding bases on the template strand
within the polymerase active site
B. polymerization proceeds in a 5' 3' direction
C. polymerization is antiparallel to template strand
D. strong processivity
E. polymerization is dependent upon the presence of an oligonucleotide primer -
ANSWER D
The enzyme that removes the RNA primer from the Okazaki fragment is:
A. DNA polymerase I
B. DNA ligase
C. helicase
D. DNA polymerase III
E. DNA gyrase - ANSWER A
