Robbins Basic Pathology
10th Edition
Author(s)Vinay Kumar; MBBS; MD;
FRCPath; Abul K. Abbas; MBBS and
Jon C. Aster; MD; PhD
Print ISBN: 9780323353175
,A patient has a germline mutation affecting a protein required for
maintaining genomic integrity. Cells from the patient show increased
accumulation of DNA damage after exposure to a DNA-damaging agent.
Which cellular function is most directly impaired?
A. Oxidative phosphorylation
B. DNA repair
C. Protein glycosylation
D. Extracellular collagen degradation
Correct Answer: B. DNA repair
,Rationale: DNA repair mechanisms detect and correct damaged DNA,
preserving genomic stability and limiting mutation accumulation.
Oxidative phosphorylation occurs in mitochondria, protein glycosylation
is associated with the endoplasmic reticulum and Golgi apparatus, and
collagen degradation is primarily mediated by extracellular proteases
such as matrix metalloproteinases.
Question 2
A mutation occurs in a coding region of a gene and changes a single
nucleotide, resulting in substitution of one amino acid for another in
the encoded protein. Which type of mutation has occurred?
A. Missense mutation
B. Nonsense mutation
C. Frameshift mutation
D. Silent mutation
Correct Answer: A. Missense mutation
Rationale: A missense mutation changes a nucleotide in a way that
substitutes one amino acid for another. A nonsense mutation creates a
premature stop codon, a frameshift results from insertion or deletion
that alters the reading frame, and a silent mutation does not change the
encoded amino acid.
Question 3
A researcher observes that two differentiated cell types contain the
same DNA but produce very different sets of proteins. Which
mechanism best explains this finding?
A. Selective expression of different genes
B. Different mitochondrial DNA in every cell
, C. Different numbers of chromosomes in each cell
D. Continuous degradation of all cellular proteins
Correct Answer: A. Selective expression of different genes
Rationale: Most differentiated cells contain the same genome but
express different subsets of genes, producing cell-specific proteins and
functions. Mitochondrial DNA contributes to cellular function but does
not account for the broad differences in protein expression. Normal
cells also retain the same chromosome complement rather than
differing chromosome numbers simply because they are differentiated.
Question 4
A patient with impaired lysosomal function develops accumulation of
undegraded material within cells. Which cellular process has been most
directly disrupted?
A. Intracellular digestion and degradation of macromolecules
B. DNA transcription
C. Extracellular matrix synthesis
D. Oxidative phosphorylation
Correct Answer: A. Intracellular digestion and degradation of
macromolecules
Rationale: Lysosomes contain acid hydrolases responsible for
degradation of proteins, lipids, nucleic acids, and carbohydrates
delivered to them through endocytic or autophagic pathways. DNA
transcription occurs in the nucleus, extracellular matrix synthesis
involves secretory pathways, and oxidative phosphorylation takes place
in mitochondria.
10th Edition
Author(s)Vinay Kumar; MBBS; MD;
FRCPath; Abul K. Abbas; MBBS and
Jon C. Aster; MD; PhD
Print ISBN: 9780323353175
,A patient has a germline mutation affecting a protein required for
maintaining genomic integrity. Cells from the patient show increased
accumulation of DNA damage after exposure to a DNA-damaging agent.
Which cellular function is most directly impaired?
A. Oxidative phosphorylation
B. DNA repair
C. Protein glycosylation
D. Extracellular collagen degradation
Correct Answer: B. DNA repair
,Rationale: DNA repair mechanisms detect and correct damaged DNA,
preserving genomic stability and limiting mutation accumulation.
Oxidative phosphorylation occurs in mitochondria, protein glycosylation
is associated with the endoplasmic reticulum and Golgi apparatus, and
collagen degradation is primarily mediated by extracellular proteases
such as matrix metalloproteinases.
Question 2
A mutation occurs in a coding region of a gene and changes a single
nucleotide, resulting in substitution of one amino acid for another in
the encoded protein. Which type of mutation has occurred?
A. Missense mutation
B. Nonsense mutation
C. Frameshift mutation
D. Silent mutation
Correct Answer: A. Missense mutation
Rationale: A missense mutation changes a nucleotide in a way that
substitutes one amino acid for another. A nonsense mutation creates a
premature stop codon, a frameshift results from insertion or deletion
that alters the reading frame, and a silent mutation does not change the
encoded amino acid.
Question 3
A researcher observes that two differentiated cell types contain the
same DNA but produce very different sets of proteins. Which
mechanism best explains this finding?
A. Selective expression of different genes
B. Different mitochondrial DNA in every cell
, C. Different numbers of chromosomes in each cell
D. Continuous degradation of all cellular proteins
Correct Answer: A. Selective expression of different genes
Rationale: Most differentiated cells contain the same genome but
express different subsets of genes, producing cell-specific proteins and
functions. Mitochondrial DNA contributes to cellular function but does
not account for the broad differences in protein expression. Normal
cells also retain the same chromosome complement rather than
differing chromosome numbers simply because they are differentiated.
Question 4
A patient with impaired lysosomal function develops accumulation of
undegraded material within cells. Which cellular process has been most
directly disrupted?
A. Intracellular digestion and degradation of macromolecules
B. DNA transcription
C. Extracellular matrix synthesis
D. Oxidative phosphorylation
Correct Answer: A. Intracellular digestion and degradation of
macromolecules
Rationale: Lysosomes contain acid hydrolases responsible for
degradation of proteins, lipids, nucleic acids, and carbohydrates
delivered to them through endocytic or autophagic pathways. DNA
transcription occurs in the nucleus, extracellular matrix synthesis
involves secretory pathways, and oxidative phosphorylation takes place
in mitochondria.
