ASU BIO 340 EXAM 3 EXAM SCRIPT 2026
COMPREHENSIVE QUESTIONS WITH
DETAILED ANSWERS GRADED A+
⩥ Which of the following forms the backbone of a polynucleotide
chain? Answer: alternating sugar and phosphate groups
⩥ Guanine and adenine are purines found in DNA Answer: true
⩥ What fraction of the nucleotides in a doubles-stranded DNA molecule
are cytosine and thymine? Answer: 50%
⩥ What is one difference between DNA replication in bacteria versus
eukaryotes? Answer: Eukaryotic chromosomes have many origins of
replication, while bacteria have only one origin of replication
⩥ What is the maximum rate between DNA replication in E. coli
Answer: 1000 nucleotides
⩥ During DNA replication in E. coli, what is the role of DnaA? Answer:
DnaA bends DNA, hydrolyzing the hydrogen bonds in the 13-mer region
of otic and creating an open complex
,⩥ Which of the following statements about DNA replication is true?
Answer: Single-strand binding proteins stabilize the open conformation
of the unwound DNA
⩥ Which of the following reagents is not required for the polymerase
chain reaction? Answer: Dideoxynucleotide triphosphate
⩥ Which of the following would you find in a Sanger sequencing
reaction but not in a polymerase chain reaction? Answer: ddNTPs
⩥ Which of the following statements about ddNTPs is true? Answer:
they have a hydrogen at the 3' carbon of the sugar
⩥ The principles of complementary base pairing and antiparallel polarity
of nucleic acid strands is a duplex are universal for the formation of
nucleic acid duplexes. What is the chemical basis for this university?
Answer:
⩥ You wish to create a mutation in which you prevent access of RNA
polymerase to the gene. Which region of a gene would you target?
Answer: promoter sequence
⩥ Which region(s) of a gene are not found within the mRNA transcript?
Answer: promoter region
,⩥ Which of the following statements regarding Nucleotide Excision
repair (NER) and Base Excision Repair (BER) is true? Answer: both
NER and BER involve the removal of one or more damaged bases by a
nuclease
⩥ How large is an origin of replication of E. coli? Answer: 245 base
pairs
⩥ Which of the following enzymatic activities is NOT involved in DNA
replication Answer: RNA- dependent DNA polymerase
⩥ Which activity of DNA polymerase is responsible for its ability to
proofread newly synthesized DNA Answer: 3'>5' exonuclease which
cleaves mismatched nucleotides
⩥ How many mutations would you expect to see in the human genome
(6x10^9) if mismatches could not be repaired? Answer: 6x10^9/10^4=
600,000 mutations
⩥ What would the consequences be of having DNA polymerase with out
5' -> 3' exonuclease activity? Answer: the RNA primer will stay
⩥ What is the correct order of enzyme action during DNA replication?
Answer: helices/topoisomerase activity, priming, DNA
, polymerization/proofreading, 5'-3' exonuclease activity/DNA
polymerization, ligation
⩥ Why is telomerase important? Answer: It is important for extension
⩥ You isolate a mutant of this gene that encodes the following protein:
N-Met-Gln-Cys-Lys-Ser-C
What mutation can give you this mutant protein Answer: Deletion of a C
⩥ Which of the following statements are FALSE? Answer: the Trp
Operon is under positive control
⩥ *LAC has both positive and negative regulation* Answer:
⩥ Trp is negative controlled Answer:
⩥ Under which of the following conditions will E. coli make large
amounts of B- galactosidase? Answer: I+O+Z+, glucose absent, lactose
present
I-OcZ+, glucose absent, lactose absent
⩥ Under what condition will E. coli make the least amount of B-
galactosidase? Answer: IsO+Z+, glucose absent, lactose present
COMPREHENSIVE QUESTIONS WITH
DETAILED ANSWERS GRADED A+
⩥ Which of the following forms the backbone of a polynucleotide
chain? Answer: alternating sugar and phosphate groups
⩥ Guanine and adenine are purines found in DNA Answer: true
⩥ What fraction of the nucleotides in a doubles-stranded DNA molecule
are cytosine and thymine? Answer: 50%
⩥ What is one difference between DNA replication in bacteria versus
eukaryotes? Answer: Eukaryotic chromosomes have many origins of
replication, while bacteria have only one origin of replication
⩥ What is the maximum rate between DNA replication in E. coli
Answer: 1000 nucleotides
⩥ During DNA replication in E. coli, what is the role of DnaA? Answer:
DnaA bends DNA, hydrolyzing the hydrogen bonds in the 13-mer region
of otic and creating an open complex
,⩥ Which of the following statements about DNA replication is true?
Answer: Single-strand binding proteins stabilize the open conformation
of the unwound DNA
⩥ Which of the following reagents is not required for the polymerase
chain reaction? Answer: Dideoxynucleotide triphosphate
⩥ Which of the following would you find in a Sanger sequencing
reaction but not in a polymerase chain reaction? Answer: ddNTPs
⩥ Which of the following statements about ddNTPs is true? Answer:
they have a hydrogen at the 3' carbon of the sugar
⩥ The principles of complementary base pairing and antiparallel polarity
of nucleic acid strands is a duplex are universal for the formation of
nucleic acid duplexes. What is the chemical basis for this university?
Answer:
⩥ You wish to create a mutation in which you prevent access of RNA
polymerase to the gene. Which region of a gene would you target?
Answer: promoter sequence
⩥ Which region(s) of a gene are not found within the mRNA transcript?
Answer: promoter region
,⩥ Which of the following statements regarding Nucleotide Excision
repair (NER) and Base Excision Repair (BER) is true? Answer: both
NER and BER involve the removal of one or more damaged bases by a
nuclease
⩥ How large is an origin of replication of E. coli? Answer: 245 base
pairs
⩥ Which of the following enzymatic activities is NOT involved in DNA
replication Answer: RNA- dependent DNA polymerase
⩥ Which activity of DNA polymerase is responsible for its ability to
proofread newly synthesized DNA Answer: 3'>5' exonuclease which
cleaves mismatched nucleotides
⩥ How many mutations would you expect to see in the human genome
(6x10^9) if mismatches could not be repaired? Answer: 6x10^9/10^4=
600,000 mutations
⩥ What would the consequences be of having DNA polymerase with out
5' -> 3' exonuclease activity? Answer: the RNA primer will stay
⩥ What is the correct order of enzyme action during DNA replication?
Answer: helices/topoisomerase activity, priming, DNA
, polymerization/proofreading, 5'-3' exonuclease activity/DNA
polymerization, ligation
⩥ Why is telomerase important? Answer: It is important for extension
⩥ You isolate a mutant of this gene that encodes the following protein:
N-Met-Gln-Cys-Lys-Ser-C
What mutation can give you this mutant protein Answer: Deletion of a C
⩥ Which of the following statements are FALSE? Answer: the Trp
Operon is under positive control
⩥ *LAC has both positive and negative regulation* Answer:
⩥ Trp is negative controlled Answer:
⩥ Under which of the following conditions will E. coli make large
amounts of B- galactosidase? Answer: I+O+Z+, glucose absent, lactose
present
I-OcZ+, glucose absent, lactose absent
⩥ Under what condition will E. coli make the least amount of B-
galactosidase? Answer: IsO+Z+, glucose absent, lactose present
