MMSC491 Exam 1, Exam 2, Exam 3 EXAM
QUESTIONS AND CORRECT VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR –
JUST RELEASED.pdf
Exam 1
Exam 2
Exam 3
EXAM 1: FOUNDATIONS OF MOLECULAR GENETICS
(Questions 1-150)
Section 1.1: DNA Structure & Replication (Q1-30)
Q1. Which of the following statements is INCORRECT regarding DNA replication?
A) DNA replication is semi-conservative because for each DNA helix only one strand serves as a template
for new DNA synthesis
B) DNA replication requires a template
C) DNA replication is semi-conservative
D) Both strands serve as templates
Correct Answer: A
Rationale: DNA replication is semi-conservative because both strands serve as templates for new DNA
synthesis, not just one strand. Each new DNA molecule contains one old strand and one newly
synthesized strand .
Q2. Regarding DNA replication and DNA synthesis, which statement is INCORRECT?
A) A DNA polymerase always requires a DNA template to synthesize a complementary DNA
B) DNA polymerase synthesizes DNA in the 5' to 3' direction
C) DNA polymerase can initiate synthesis without a primer
D) DNA polymerase requires a primer to begin synthesis
Correct Answer: C
,Rationale: DNA polymerase cannot initiate synthesis on its own; it requires a primer (RNA primer
synthesized by primase) to provide a free 3'-OH group for nucleotide addition .
Q3. Which of the following best describes the role of helicase in DNA replication?
A) It synthesizes RNA primers to initiate DNA synthesis
B) It unwinds the double helix by breaking hydrogen bonds between base pairs
C) It synthesizes new DNA strands in the 5' to 3' direction
D) It seals nicks in the DNA backbone
Correct Answer: B
Rationale: Helicase unwinds the DNA double helix by breaking hydrogen bonds between base pairs,
creating a replication fork. Primase synthesizes RNA primers. DNA polymerase synthesizes new strands.
Ligase seals nicks .
Q4. Regarding the structure of bases in nucleic acids, which statement is INCORRECT?
A) Purines carry an amino group, unlike pyrimidines
B) Both purines and pyrimidines contain nitrogen
C) Purines have a double-ring structure
D) Pyrimidines have a single-ring structure
Correct Answer: A
Rationale: Both purines and pyrimidines can carry amino groups. The key difference is that purines
(adenine, guanine) have a double-ring structure, while pyrimidines (cytosine, thymine, uracil) have a
single-ring structure .
Q5. Regarding the sugar residues in nucleic acids, which statement is INCORRECT?
A) The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike those in an
RNA strand
B) DNA contains deoxyribose
C) RNA contains ribose
D) Both DNA and RNA sugars have 5 carbon atoms
Correct Answer: A
Rationale: In DNA, the 2' position lacks a hydroxyl group (deoxyribose), while in RNA, the 2' position
has a hydroxyl group. The internal sugar residues in RNA have free hydroxyl groups, not DNA .
Q6. Regarding polypeptide structure, which statement is INCORRECT?
A) A polypeptide is a polymer composed of a linear sequence of amino acids
,B) A polypeptide normally adopts a rod-like conformation, with the side chains orientated in the same
direction relative to the polypeptide backbone
C) The amino acids within a polypeptide are joined by a covalent bond known as a peptide bond
D) Peptide bonds form by a condensation reaction between the amino group of an amino acid and the
carboxyl group of its neighbor
Correct Answer: B
Rationale: A polypeptide does NOT normally adopt a rod-like conformation. Polypeptides fold into
complex three-dimensional structures, including alpha-helices, beta-sheets, and globular domains .
Q7. Regarding protein structure, which statements are INCORRECT? (Select all that apply)
A) The primary structure is the linear sequence of amino acids
B) The secondary structure is the path followed by the polypeptide backbone over its length
C) The secondary structure of every protein contains an alpha-helix
D) The structure of an alpha-helix is primarily determined by hydrogen bonding between chemical
groups on the side chains
Correct Answer: C, D
Rationale: Not every protein contains an alpha-helix; many proteins consist primarily of beta-sheets or
other secondary structures. The alpha-helix structure is primarily determined by hydrogen bonding
between the backbone carbonyl and amino groups, not side chains .
Q8. Regarding RNA structure, which statement is FALSE?
A) Unlike DNA, RNAs are unmethylated, and only the four standard bases - A, C, G and U - are found in
RNAs
B) The primary structure of an RNA is the linear sequence of nucleotides
C) The secondary structure of an RNA is dominated by hydrogen bonding between bases on the same
strand
D) Stem-loop structures are common in RNA and consist of complementary sequences that form stable
base pairs, separated by a short sequence of unpaired bases
Correct Answer: A
Rationale: RNAs do contain modified bases, including methylation. Transfer RNAs and ribosomal RNAs
in particular contain numerous modified nucleotides .
Q9. Which statement is FALSE regarding ribosomes? (Select all that apply)
, A) A ribosome is a large ribonucleoprotein that contains multiple different types of RNA but just one type
of protein
B) During translation, a ribosome binds to the 5' end of an mRNA, slides along it until the initiator AUG
codon is identified, and continues until reaching an in-frame termination codon
C) The single type of ribosomal protein is a crucially important peptidyltransferase
D) The peptidyltransferase catalyzes the condensation reaction that allows joining of amino acids using
peptide bonds
Correct Answer: A, C
Rationale: Ribosomes contain multiple types of proteins, not just one. The peptidyltransferase activity is
catalyzed by ribosomal RNA (rRNA), not protein .
Q10. Which statements are FALSE regarding translation?
A) During translation, the individual codons of an mRNA are "read" by transient hydrogen bonding to a
complementary anticodon sequence on a transfer RNA
B) According to their anticodon, transfer RNAs usually have a specific amino acid attached to their 3' end
C) When the anticodon of a tRNA binds to a codon with a suitably complementary sequence, the amino
acid is released and becomes part of a polypeptide
D) Translation terminates at an in-frame termination codon (UAA, UAG, or UGA) because for these
codons, there are no transfer RNAs with a complementary anticodon sequence
Correct Answer: None (All statements are true)
Rationale: All statements accurately describe the process of translation .
Q11. Which statements are FALSE regarding stem-loop structures? (Select all that apply)
A) Stem-loop structures are formed by base pairing of complementary sequences that are separated by a
short sequence of nucleotides with unpaired bases
B) Stem-loop structures are common occurrences in both DNA and RNA
C) Stem-loop structures are important for structural reasons only
D) Stem-loop structures can be important functional elements
Correct Answer: B, C
Rationale: Stem-loop structures are primarily common in RNA, though they can occur in DNA. They are
not important for structural reasons only; they serve as functional elements in processes like transcription
termination and miRNA processing .
Q12. Which statement regarding the structure of nucleic acids and proteins is FALSE?
QUESTIONS AND CORRECT VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR –
JUST RELEASED.pdf
Exam 1
Exam 2
Exam 3
EXAM 1: FOUNDATIONS OF MOLECULAR GENETICS
(Questions 1-150)
Section 1.1: DNA Structure & Replication (Q1-30)
Q1. Which of the following statements is INCORRECT regarding DNA replication?
A) DNA replication is semi-conservative because for each DNA helix only one strand serves as a template
for new DNA synthesis
B) DNA replication requires a template
C) DNA replication is semi-conservative
D) Both strands serve as templates
Correct Answer: A
Rationale: DNA replication is semi-conservative because both strands serve as templates for new DNA
synthesis, not just one strand. Each new DNA molecule contains one old strand and one newly
synthesized strand .
Q2. Regarding DNA replication and DNA synthesis, which statement is INCORRECT?
A) A DNA polymerase always requires a DNA template to synthesize a complementary DNA
B) DNA polymerase synthesizes DNA in the 5' to 3' direction
C) DNA polymerase can initiate synthesis without a primer
D) DNA polymerase requires a primer to begin synthesis
Correct Answer: C
,Rationale: DNA polymerase cannot initiate synthesis on its own; it requires a primer (RNA primer
synthesized by primase) to provide a free 3'-OH group for nucleotide addition .
Q3. Which of the following best describes the role of helicase in DNA replication?
A) It synthesizes RNA primers to initiate DNA synthesis
B) It unwinds the double helix by breaking hydrogen bonds between base pairs
C) It synthesizes new DNA strands in the 5' to 3' direction
D) It seals nicks in the DNA backbone
Correct Answer: B
Rationale: Helicase unwinds the DNA double helix by breaking hydrogen bonds between base pairs,
creating a replication fork. Primase synthesizes RNA primers. DNA polymerase synthesizes new strands.
Ligase seals nicks .
Q4. Regarding the structure of bases in nucleic acids, which statement is INCORRECT?
A) Purines carry an amino group, unlike pyrimidines
B) Both purines and pyrimidines contain nitrogen
C) Purines have a double-ring structure
D) Pyrimidines have a single-ring structure
Correct Answer: A
Rationale: Both purines and pyrimidines can carry amino groups. The key difference is that purines
(adenine, guanine) have a double-ring structure, while pyrimidines (cytosine, thymine, uracil) have a
single-ring structure .
Q5. Regarding the sugar residues in nucleic acids, which statement is INCORRECT?
A) The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike those in an
RNA strand
B) DNA contains deoxyribose
C) RNA contains ribose
D) Both DNA and RNA sugars have 5 carbon atoms
Correct Answer: A
Rationale: In DNA, the 2' position lacks a hydroxyl group (deoxyribose), while in RNA, the 2' position
has a hydroxyl group. The internal sugar residues in RNA have free hydroxyl groups, not DNA .
Q6. Regarding polypeptide structure, which statement is INCORRECT?
A) A polypeptide is a polymer composed of a linear sequence of amino acids
,B) A polypeptide normally adopts a rod-like conformation, with the side chains orientated in the same
direction relative to the polypeptide backbone
C) The amino acids within a polypeptide are joined by a covalent bond known as a peptide bond
D) Peptide bonds form by a condensation reaction between the amino group of an amino acid and the
carboxyl group of its neighbor
Correct Answer: B
Rationale: A polypeptide does NOT normally adopt a rod-like conformation. Polypeptides fold into
complex three-dimensional structures, including alpha-helices, beta-sheets, and globular domains .
Q7. Regarding protein structure, which statements are INCORRECT? (Select all that apply)
A) The primary structure is the linear sequence of amino acids
B) The secondary structure is the path followed by the polypeptide backbone over its length
C) The secondary structure of every protein contains an alpha-helix
D) The structure of an alpha-helix is primarily determined by hydrogen bonding between chemical
groups on the side chains
Correct Answer: C, D
Rationale: Not every protein contains an alpha-helix; many proteins consist primarily of beta-sheets or
other secondary structures. The alpha-helix structure is primarily determined by hydrogen bonding
between the backbone carbonyl and amino groups, not side chains .
Q8. Regarding RNA structure, which statement is FALSE?
A) Unlike DNA, RNAs are unmethylated, and only the four standard bases - A, C, G and U - are found in
RNAs
B) The primary structure of an RNA is the linear sequence of nucleotides
C) The secondary structure of an RNA is dominated by hydrogen bonding between bases on the same
strand
D) Stem-loop structures are common in RNA and consist of complementary sequences that form stable
base pairs, separated by a short sequence of unpaired bases
Correct Answer: A
Rationale: RNAs do contain modified bases, including methylation. Transfer RNAs and ribosomal RNAs
in particular contain numerous modified nucleotides .
Q9. Which statement is FALSE regarding ribosomes? (Select all that apply)
, A) A ribosome is a large ribonucleoprotein that contains multiple different types of RNA but just one type
of protein
B) During translation, a ribosome binds to the 5' end of an mRNA, slides along it until the initiator AUG
codon is identified, and continues until reaching an in-frame termination codon
C) The single type of ribosomal protein is a crucially important peptidyltransferase
D) The peptidyltransferase catalyzes the condensation reaction that allows joining of amino acids using
peptide bonds
Correct Answer: A, C
Rationale: Ribosomes contain multiple types of proteins, not just one. The peptidyltransferase activity is
catalyzed by ribosomal RNA (rRNA), not protein .
Q10. Which statements are FALSE regarding translation?
A) During translation, the individual codons of an mRNA are "read" by transient hydrogen bonding to a
complementary anticodon sequence on a transfer RNA
B) According to their anticodon, transfer RNAs usually have a specific amino acid attached to their 3' end
C) When the anticodon of a tRNA binds to a codon with a suitably complementary sequence, the amino
acid is released and becomes part of a polypeptide
D) Translation terminates at an in-frame termination codon (UAA, UAG, or UGA) because for these
codons, there are no transfer RNAs with a complementary anticodon sequence
Correct Answer: None (All statements are true)
Rationale: All statements accurately describe the process of translation .
Q11. Which statements are FALSE regarding stem-loop structures? (Select all that apply)
A) Stem-loop structures are formed by base pairing of complementary sequences that are separated by a
short sequence of nucleotides with unpaired bases
B) Stem-loop structures are common occurrences in both DNA and RNA
C) Stem-loop structures are important for structural reasons only
D) Stem-loop structures can be important functional elements
Correct Answer: B, C
Rationale: Stem-loop structures are primarily common in RNA, though they can occur in DNA. They are
not important for structural reasons only; they serve as functional elements in processes like transcription
termination and miRNA processing .
Q12. Which statement regarding the structure of nucleic acids and proteins is FALSE?
