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
,Question 1
A researcher compares two human cells from the same patient. The
cells contain the same DNA sequence, yet one produces large amounts
of collagen while the other produces albumin. Which mechanism best
explains this difference?
A. Different numbers of chromosomes in each cell
B. Selective expression of different genes
C. Different genetic codes in the two cells
D. Irreversible mutation of all nonexpressed genes
,Correct Answer: B. Selective expression of different genes
Rationale:
Cells with the same genome can have very different structures and
functions because they selectively express different subsets of genes.
This regulated gene expression allows specialized cells to synthesize
proteins appropriate for their functions. Option A is incorrect because
normal differentiated cells generally retain the same chromosome
complement; C is incorrect because the genetic code is essentially
shared among cells; D is incorrect because genes that are not expressed
are not necessarily permanently mutated or deleted.
Question 2
A mutation occurs in a gene responsible for producing a protein
involved in DNA repair. Which cellular consequence is most likely if the
mutation substantially reduces the protein's function?
A. Increased accuracy of DNA replication
B. Reduced accumulation of genomic abnormalities
C. Increased susceptibility to mutations during cell replication
D. Immediate enhancement of mitochondrial ATP production
Correct Answer: C. Increased susceptibility to mutations during cell
replication
Rationale:
DNA repair mechanisms preserve genomic integrity by identifying and
correcting DNA damage. Loss of repair capacity permits replication
errors and other DNA abnormalities to accumulate, increasing genomic
instability. Option A is the opposite of the expected effect, B would not
occur with impaired repair, and D is unrelated to the primary function
of DNA repair proteins.
, Question 3
A biopsy specimen shows cells with abundant rough endoplasmic
reticulum and prominent Golgi apparatus. Which cellular function is
most strongly suggested by this morphology?
A. Synthesis and secretion of proteins
B. Oxidation of fatty acids
C. Storage of intracellular calcium
D. Degradation of damaged organelles by lysosomes
Correct Answer: A. Synthesis and secretion of proteins
Rationale:
The rough endoplasmic reticulum is specialized for synthesis of proteins
destined for secretion or insertion into membranes, while the Golgi
apparatus modifies, sorts, and packages these proteins. Cells with high
secretory activity therefore commonly contain prominent rough ER and
Golgi structures. Fatty acid oxidation is primarily associated with
mitochondria and peroxisomes, calcium storage is especially important
in the endoplasmic reticulum, and lysosomes mediate intracellular
degradation.
Question 4
A cell internalizes a protein through receptor-mediated endocytosis.
After entering the cell, the vesicle fuses with an organelle that
maintains an acidic environment and helps sort or process its contents.
Which organelle is primarily responsible for this function?
A. Nucleus
B. Endosome
C. Peroxisome
D. Ribosome
10th Edition
Author(s)Vinay Kumar; MBBS; MD;
FRCPath; Abul K. Abbas; MBBS and
Jon C. Aster; MD; PhD
Print ISBN: 9780323353175
,Question 1
A researcher compares two human cells from the same patient. The
cells contain the same DNA sequence, yet one produces large amounts
of collagen while the other produces albumin. Which mechanism best
explains this difference?
A. Different numbers of chromosomes in each cell
B. Selective expression of different genes
C. Different genetic codes in the two cells
D. Irreversible mutation of all nonexpressed genes
,Correct Answer: B. Selective expression of different genes
Rationale:
Cells with the same genome can have very different structures and
functions because they selectively express different subsets of genes.
This regulated gene expression allows specialized cells to synthesize
proteins appropriate for their functions. Option A is incorrect because
normal differentiated cells generally retain the same chromosome
complement; C is incorrect because the genetic code is essentially
shared among cells; D is incorrect because genes that are not expressed
are not necessarily permanently mutated or deleted.
Question 2
A mutation occurs in a gene responsible for producing a protein
involved in DNA repair. Which cellular consequence is most likely if the
mutation substantially reduces the protein's function?
A. Increased accuracy of DNA replication
B. Reduced accumulation of genomic abnormalities
C. Increased susceptibility to mutations during cell replication
D. Immediate enhancement of mitochondrial ATP production
Correct Answer: C. Increased susceptibility to mutations during cell
replication
Rationale:
DNA repair mechanisms preserve genomic integrity by identifying and
correcting DNA damage. Loss of repair capacity permits replication
errors and other DNA abnormalities to accumulate, increasing genomic
instability. Option A is the opposite of the expected effect, B would not
occur with impaired repair, and D is unrelated to the primary function
of DNA repair proteins.
, Question 3
A biopsy specimen shows cells with abundant rough endoplasmic
reticulum and prominent Golgi apparatus. Which cellular function is
most strongly suggested by this morphology?
A. Synthesis and secretion of proteins
B. Oxidation of fatty acids
C. Storage of intracellular calcium
D. Degradation of damaged organelles by lysosomes
Correct Answer: A. Synthesis and secretion of proteins
Rationale:
The rough endoplasmic reticulum is specialized for synthesis of proteins
destined for secretion or insertion into membranes, while the Golgi
apparatus modifies, sorts, and packages these proteins. Cells with high
secretory activity therefore commonly contain prominent rough ER and
Golgi structures. Fatty acid oxidation is primarily associated with
mitochondria and peroxisomes, calcium storage is especially important
in the endoplasmic reticulum, and lysosomes mediate intracellular
degradation.
Question 4
A cell internalizes a protein through receptor-mediated endocytosis.
After entering the cell, the vesicle fuses with an organelle that
maintains an acidic environment and helps sort or process its contents.
Which organelle is primarily responsible for this function?
A. Nucleus
B. Endosome
C. Peroxisome
D. Ribosome
