NURS 6233 MIDTERM: ADVANCED GENETICS,
GENOMICS & PATHOPHYSIOLOGY QUESTION
PRACTICE EXAM WITH RATIONALES Latest
2026/2027 Updated Content
1. Which component of DNA forms the "backbone" of the double helix?
A) Nitrogenous bases
B) Hydrogen bonds
C) Sugar-phosphate groups
D) Amino acids
Answer: C
Rationale: The sugar-phosphate backbone (deoxyribose sugar + phosphate
groups) forms the structural outer framework of DNA. Nitrogenous bases (A) pair
internally, hydrogen bonds (B) connect base pairs, and amino acids (D) are protein
components, not DNA.
2. What type of bond connects complementary nitrogenous bases in DNA?
A) Covalent bond
B) Ionic bond
C) Hydrogen bond
D) Peptide bond
Answer: C
Rationale: Hydrogen bonds (weak, reversible) connect A-T (2 bonds) and G-C (3
bonds). Covalent bonds (A) connect nucleotides in the backbone, ionic bonds (B)
involve electron transfer, and peptide bonds (D) connect amino acids in proteins.
3. Which RNA type carries genetic information from DNA to the ribosome?
A) tRNA (transfer RNA)
B) rRNA (ribosomal RNA)
C) mRNA (messenger RNA)
D) snRNA (small nuclear RNA)
,Answer: C
Rationale: mRNA carries the genetic code from DNA (transcription) to ribosomes
for protein synthesis (translation). tRNA (A) brings amino acids, rRNA (B) forms
ribosome structure, snRNA (D) aids RNA processing.
4. What is the "start codon" for protein synthesis?
A) UAA
B) UAG
C) AUG
D) UGA
Answer: C
Rationale: AUG (adenine-uracil-guanine) is the start codon that signals translation
begins and codes for methionine. UAA (A), UAG (B), and UGA (D) are STOP
codons that terminate protein synthesis.
5. Which enzyme is responsible for DNA replication?
A) RNA polymerase
B) DNA polymerase
C) Helicase
D) Ligase
Answer: B
Rationale: DNA polymerase synthesizes new DNA strands by adding nucleotides
during replication. RNA polymerase (A) makes RNA from DNA, helicase (C)
unwinds DNA, and ligase (D) joins DNA fragments.
6. What does "semiconservative replication" mean?
A) Both new DNA strands are completely new
B) Each new DNA molecule has one old and one new strand
C) DNA replication is error-free
D) Only one strand is replicated
Answer: B
Rationale: Semiconservative replication means each daughter DNA molecule
contains one parental (original) strand and one newly synthesized strand. Option A
,describes conservative replication (incorrect), C is false (errors occur), and D
describes asymmetric replication.
7. Which mutation type is MOST likely to cause a frameshift?
A) Substitution
B) Insertion of 1 nucleotide
C) Deletion of 3 nucleotides
D) Silent mutation
Answer: B
Rationale: Insertion or deletion of nucleotides NOT in multiples of 3 causes
frameshift, changing all downstream codons. Insertion of 1 nucleotide (B) shifts
the reading frame. Substitution (A) and deletion of 3 (C, in-frame) don't cause
frameshift. Silent mutations (D) don't change protein.
8. What is the function of telomeres?
A) Code for essential proteins
B) Protect chromosome ends from degradation
C) Initiate DNA replication
D) Connect chromosomes to spindle fibers
Answer: B
Rationale: Telomeres are repetitive DNA sequences at chromosome ends that
protect them from degradation and fusion. They shorten with each cell division.
They don't code proteins (A), initiate replication (C), or connect to spindle (D =
centromere).
9. Which process converts DNA to RNA?
A) Translation
B) Transcription
C) Replication
D) Reverse transcription
Answer: B
Rationale: Transcription synthesizes RNA from a DNA template (DNA → RNA).
Translation (A) makes protein from RNA (RNA → protein), replication (C) copies
, DNA (DNA → DNA), and reverse transcription (D) makes DNA from RNA (RNA
→ DNA, in retroviruses).
10. What is a "silent mutation"?
A) Mutation that kills the cell
B) Mutation that changes amino acid but not protein function
C) Mutation that doesn't change the amino acid sequence
D) Mutation that stops protein synthesis
Answer: C
Rationale: Silent mutations change the DNA nucleotide but NOT the amino acid
(due to codon redundancy, e.g., GAA → GAG both code for glutamate). Option B
describes missense mutation, D describes nonsense mutation.
11. Which chromosomal abnormality causes Down syndrome?
A) Monosomy 18
B) Trisomy 21
C) Trisomy 13
D) Deletion 5p
Answer: B
Rationale: Down syndrome = Trisomy 21 (three copies of chromosome 21).
Monosomy 18 (A) = Edwards syndrome, Trisomy 13 (C) = Patau syndrome,
Deletion 5p (D) = Cri-du-chat syndrome.
12. What is the purpose of "proofreading" by DNA polymerase?
A) Speed up replication
B) Remove incorrectly paired nucleotides
C) Add telomeres
D) Unwind DNA
Answer: B
Rationale: DNA polymerase proofreading removes mispaired nucleotides during
replication, reducing mutation rate from 1/10⁵ to 1/10⁹. It doesn't affect speed (A),
add telomeres (C), or unwind DNA (D = helicase).
GENOMICS & PATHOPHYSIOLOGY QUESTION
PRACTICE EXAM WITH RATIONALES Latest
2026/2027 Updated Content
1. Which component of DNA forms the "backbone" of the double helix?
A) Nitrogenous bases
B) Hydrogen bonds
C) Sugar-phosphate groups
D) Amino acids
Answer: C
Rationale: The sugar-phosphate backbone (deoxyribose sugar + phosphate
groups) forms the structural outer framework of DNA. Nitrogenous bases (A) pair
internally, hydrogen bonds (B) connect base pairs, and amino acids (D) are protein
components, not DNA.
2. What type of bond connects complementary nitrogenous bases in DNA?
A) Covalent bond
B) Ionic bond
C) Hydrogen bond
D) Peptide bond
Answer: C
Rationale: Hydrogen bonds (weak, reversible) connect A-T (2 bonds) and G-C (3
bonds). Covalent bonds (A) connect nucleotides in the backbone, ionic bonds (B)
involve electron transfer, and peptide bonds (D) connect amino acids in proteins.
3. Which RNA type carries genetic information from DNA to the ribosome?
A) tRNA (transfer RNA)
B) rRNA (ribosomal RNA)
C) mRNA (messenger RNA)
D) snRNA (small nuclear RNA)
,Answer: C
Rationale: mRNA carries the genetic code from DNA (transcription) to ribosomes
for protein synthesis (translation). tRNA (A) brings amino acids, rRNA (B) forms
ribosome structure, snRNA (D) aids RNA processing.
4. What is the "start codon" for protein synthesis?
A) UAA
B) UAG
C) AUG
D) UGA
Answer: C
Rationale: AUG (adenine-uracil-guanine) is the start codon that signals translation
begins and codes for methionine. UAA (A), UAG (B), and UGA (D) are STOP
codons that terminate protein synthesis.
5. Which enzyme is responsible for DNA replication?
A) RNA polymerase
B) DNA polymerase
C) Helicase
D) Ligase
Answer: B
Rationale: DNA polymerase synthesizes new DNA strands by adding nucleotides
during replication. RNA polymerase (A) makes RNA from DNA, helicase (C)
unwinds DNA, and ligase (D) joins DNA fragments.
6. What does "semiconservative replication" mean?
A) Both new DNA strands are completely new
B) Each new DNA molecule has one old and one new strand
C) DNA replication is error-free
D) Only one strand is replicated
Answer: B
Rationale: Semiconservative replication means each daughter DNA molecule
contains one parental (original) strand and one newly synthesized strand. Option A
,describes conservative replication (incorrect), C is false (errors occur), and D
describes asymmetric replication.
7. Which mutation type is MOST likely to cause a frameshift?
A) Substitution
B) Insertion of 1 nucleotide
C) Deletion of 3 nucleotides
D) Silent mutation
Answer: B
Rationale: Insertion or deletion of nucleotides NOT in multiples of 3 causes
frameshift, changing all downstream codons. Insertion of 1 nucleotide (B) shifts
the reading frame. Substitution (A) and deletion of 3 (C, in-frame) don't cause
frameshift. Silent mutations (D) don't change protein.
8. What is the function of telomeres?
A) Code for essential proteins
B) Protect chromosome ends from degradation
C) Initiate DNA replication
D) Connect chromosomes to spindle fibers
Answer: B
Rationale: Telomeres are repetitive DNA sequences at chromosome ends that
protect them from degradation and fusion. They shorten with each cell division.
They don't code proteins (A), initiate replication (C), or connect to spindle (D =
centromere).
9. Which process converts DNA to RNA?
A) Translation
B) Transcription
C) Replication
D) Reverse transcription
Answer: B
Rationale: Transcription synthesizes RNA from a DNA template (DNA → RNA).
Translation (A) makes protein from RNA (RNA → protein), replication (C) copies
, DNA (DNA → DNA), and reverse transcription (D) makes DNA from RNA (RNA
→ DNA, in retroviruses).
10. What is a "silent mutation"?
A) Mutation that kills the cell
B) Mutation that changes amino acid but not protein function
C) Mutation that doesn't change the amino acid sequence
D) Mutation that stops protein synthesis
Answer: C
Rationale: Silent mutations change the DNA nucleotide but NOT the amino acid
(due to codon redundancy, e.g., GAA → GAG both code for glutamate). Option B
describes missense mutation, D describes nonsense mutation.
11. Which chromosomal abnormality causes Down syndrome?
A) Monosomy 18
B) Trisomy 21
C) Trisomy 13
D) Deletion 5p
Answer: B
Rationale: Down syndrome = Trisomy 21 (three copies of chromosome 21).
Monosomy 18 (A) = Edwards syndrome, Trisomy 13 (C) = Patau syndrome,
Deletion 5p (D) = Cri-du-chat syndrome.
12. What is the purpose of "proofreading" by DNA polymerase?
A) Speed up replication
B) Remove incorrectly paired nucleotides
C) Add telomeres
D) Unwind DNA
Answer: B
Rationale: DNA polymerase proofreading removes mispaired nucleotides during
replication, reducing mutation rate from 1/10⁵ to 1/10⁹. It doesn't affect speed (A),
add telomeres (C), or unwind DNA (D = helicase).
