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 laboratory investigates a human cell in which the nucleus has been
removed experimentally while the plasma membrane remains intact.
Which cellular function would be most directly impaired?
A. Diffusion of oxygen across the plasma membrane
B. Synthesis of most cellular proteins
C. Formation of the phospholipid bilayer
D. Passive movement of water across the membrane
Correct Answer: B. Synthesis of most cellular proteins
,Rationale:
The nucleus contains the genome and provides the DNA template for
transcription of messenger RNA required for protein synthesis. Oxygen
diffusion, membrane structure, and osmotic water movement can occur
without direct nuclear participation for a time. The absence of the
nucleus therefore most directly disrupts gene expression and the
production of many proteins.
Question 2
A patient has a mutation that prevents a newly synthesized protein
from entering the endoplasmic reticulum. Which consequence is most
likely?
A. Impaired synthesis of proteins destined for secretion
B. Increased replication of mitochondrial DNA
C. Failure of cytosolic glycolysis
D. Increased degradation of nuclear DNA
Correct Answer: A. Impaired synthesis of proteins destined for secretion
Rationale:
Proteins that are secreted or incorporated into lysosomal or plasma
membranes are synthesized by ribosomes associated with the rough
endoplasmic reticulum and enter the endoplasmic reticulum during
translation. Mitochondrial DNA replication, glycolysis, and nuclear DNA
degradation are not primarily dependent on entry into the endoplasmic
reticulum. A defect in this targeting step therefore compromises the
production and processing of many secretory proteins.
Question 3
, A researcher identifies a cell with an extensive network of smooth
endoplasmic reticulum. Which function would most likely be prominent
in this cell?
A. Synthesis of ribosomal RNA
B. Detoxification of lipid-soluble compounds
C. Packaging of chromosomes during mitosis
D. Production of extracellular collagen
Correct Answer: B. Detoxification of lipid-soluble compounds
Rationale:
Smooth endoplasmic reticulum is important in lipid synthesis, drug
detoxification, and calcium storage, particularly in hepatocytes.
Ribosomal RNA is synthesized primarily in the nucleolus, chromosomes
are organized during cell division within the nucleus, and collagen
synthesis begins on rough endoplasmic reticulum-associated ribosomes.
Thus, extensive smooth endoplasmic reticulum suggests strong
detoxification and lipid-related activity.
Question 4
A mutation eliminates functional lysosomal enzymes in a cell. Which
process would be most directly affected?
A. Degradation of intracellular macromolecules
B. Synthesis of ATP from glucose
C. Transcription of nuclear DNA
D. Assembly of microtubules
Correct Answer: A. Degradation of intracellular macromolecules
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 laboratory investigates a human cell in which the nucleus has been
removed experimentally while the plasma membrane remains intact.
Which cellular function would be most directly impaired?
A. Diffusion of oxygen across the plasma membrane
B. Synthesis of most cellular proteins
C. Formation of the phospholipid bilayer
D. Passive movement of water across the membrane
Correct Answer: B. Synthesis of most cellular proteins
,Rationale:
The nucleus contains the genome and provides the DNA template for
transcription of messenger RNA required for protein synthesis. Oxygen
diffusion, membrane structure, and osmotic water movement can occur
without direct nuclear participation for a time. The absence of the
nucleus therefore most directly disrupts gene expression and the
production of many proteins.
Question 2
A patient has a mutation that prevents a newly synthesized protein
from entering the endoplasmic reticulum. Which consequence is most
likely?
A. Impaired synthesis of proteins destined for secretion
B. Increased replication of mitochondrial DNA
C. Failure of cytosolic glycolysis
D. Increased degradation of nuclear DNA
Correct Answer: A. Impaired synthesis of proteins destined for secretion
Rationale:
Proteins that are secreted or incorporated into lysosomal or plasma
membranes are synthesized by ribosomes associated with the rough
endoplasmic reticulum and enter the endoplasmic reticulum during
translation. Mitochondrial DNA replication, glycolysis, and nuclear DNA
degradation are not primarily dependent on entry into the endoplasmic
reticulum. A defect in this targeting step therefore compromises the
production and processing of many secretory proteins.
Question 3
, A researcher identifies a cell with an extensive network of smooth
endoplasmic reticulum. Which function would most likely be prominent
in this cell?
A. Synthesis of ribosomal RNA
B. Detoxification of lipid-soluble compounds
C. Packaging of chromosomes during mitosis
D. Production of extracellular collagen
Correct Answer: B. Detoxification of lipid-soluble compounds
Rationale:
Smooth endoplasmic reticulum is important in lipid synthesis, drug
detoxification, and calcium storage, particularly in hepatocytes.
Ribosomal RNA is synthesized primarily in the nucleolus, chromosomes
are organized during cell division within the nucleus, and collagen
synthesis begins on rough endoplasmic reticulum-associated ribosomes.
Thus, extensive smooth endoplasmic reticulum suggests strong
detoxification and lipid-related activity.
Question 4
A mutation eliminates functional lysosomal enzymes in a cell. Which
process would be most directly affected?
A. Degradation of intracellular macromolecules
B. Synthesis of ATP from glucose
C. Transcription of nuclear DNA
D. Assembly of microtubules
Correct Answer: A. Degradation of intracellular macromolecules
