MIC 102 FINAL QUESTIONS & ANSWERS
Which of the following are NOT influenced by cell size:
A. Type of microscopy used to image cells
B.Acquisition of nutrients from the environment
C. Microbial growth rate (how quickly they replicate)
D. Surface area/volume ratio
E. Presence of a phospholipid membrane - Answers -E. Presence of a phospholipid
membrane
All organisms have this
Which statement provides evidence that the Eukarya lineage arose by the "ingestion" of
an ancestral bacterium by an ancestral archaeaon (cell from Archaea lineage)?
A. All eukaryotic organisms produce O2
B. Eukaryotic DNA replication and transcription enzymes are most similar to the the
equivalent enzymes in modern Archaea
C. Modern day Archaea have been observed to ingest Bacteria
D. Mitochondria resemble modern cyanobacteria in appearance and metabolism
E. Chloroplasts have a larger genome than modern cyanobacteria - Answers -B.
Eukaryotic DNA replication and transcription enzymes are most similar to the the
equivalent enzymes in modern Archaea
Because the DNA replication and transcriptional machinery of eukaryotic cells is most
similar to the equivalent enzymes in Archaea, and mitochondrial genes most closely
resemble equivalent genes found in Bacteria, it is thought that an archaeaon engulfed a
bacterium. This endosymbiont became fixed and degraded over time into an organelle,
the mitochondrion.
True or False
All cellular organisms grow best at 37C although some extremophiles can tolerate much
higher or lower temperatures. - Answers -False
Extremophiles are highly adapted to the environments they are found in and would find
"normal" human temperatures incompatible with survival and/or growth.
Which molecule is NOT a constituent of the gram-negative bacterial envelope?
A. Lipopolysaccharide
B. Periplasm
C. Lipoteichoic acid
D. Peptidoglycan
E. C and D - Answers -C. Lipoteichoic acid
,Note: Lipoteichoic acid is the true answer, but because the textbook had not yet defined
"peptidoglycan", I will accept peptidoglycan as well. Due to limitations in Canvas, the
only way I can give credit for answers C, D, and C and D is to give all students credit for
the question.
Lipopolysaccharide and the periplasm are found only in gram-negative cells.
Peptidoglycan is found in (nearly) all Bacteria, although gram-positive cells have
significantly more layers of this "cell wall" material. Lipoteichoic acid (and wall teichoic
acid) acid are found only in the envelope of gram-positive cells.
True or False
All microscopes use light or electrons to image cellular structures. - Answers -False
Scanning probe microscopes use a metal tip to probe the contours and properties of
surface structures.
Which type of cell is most susceptible to osmotic lysis in an environment with a very low
concentration of solutes (hypotonic)?
A. Gram-negative cell
B. Gram-positive cell
C. Mycoplasma
D. Acid-fast mycobacterium
E. Archaeon with pseudomurein - Answers -C. Mycoplasma
p35-45 Mycoplasma are the only prokaryotic group listed that do not have a cell wall to
resist high osmotic pressure caused by water moving into the solute-rich cell. While
Mycoplasma are highly successful inside the relatively isotonic environment inside a
host's body, they do not fare well in hypotonic environments or even tissue culture.
Which of the following cellular structures self-assemble (i.e. purified monomers can
assemble into the structure without added factors or the input of energy)?
A. Flagellar filament
B. Phospholipid bilayer
C. Pili
D. S layer
E. A and B
F. C and D
G. A, B, & C - Answers -G. Flagellar filament, Phospholipid Bilayer, Pili
p49-51 Pili are built of monomers of the protein pilin that are added to the base of the
pilus filament. Flagellin aggregates spontaneously at the tip of the flagellar filament
during flagellar assembly. p44 The S-layer is a lattice of a single protein that will self-
assemble into highly-ordered arrays.
What distinguishes an organelle from a carboxysome or enterosome?
, A. Organelles contain DNA
B. The function of organelles is to compartmentalize metabolic activities
C. Carboxysomes and enterosomes are enclosed within a membrane
D. A and B
E. A, B, and C - Answers -A. Organelles contain DNA
p71-74 Carboxysomes and enterosomes are protein-enclosed compartments where
bacteria concentrate the enzymes and substrates for carbon fixation or propanediol and
ethanolamine metabolism, respectively. There is no evidence to suggest they are
derived from an ancient endosymbiont—such as chloroplasts and mitochondria are
thought to be—including the absence of a (much reduced) genome.
DNA may be observed in which form inside of Bacterial cells?
A. Circular chromosomes
B. Linear plasmids
C. Bound by DNA-condensing RNA molecules
D. Attached to high concentrations of anions - Answers -A. Circular chromosomes
p64-68 Most Bacteria have a single circular chromosome bound by DNA-condensing
proteins (much like the histones that organize eukaryotic DNA). Positively-charged
cations in the cytoplasm reduce the electrostatic repulsion of negatively-charged DNA
and allow its condensation into higher-ordered loops and supercoiled structures.
Bacteria may also have circular plasmids, which encode functions not essential for
survival (note: a cell may be "cured" of a plasmid but never of a chromosome).
True or False
Only prokaryotes can transcribe and translate a gene at the same time. - Answers -
True
True
In eukaryotes, transcription and translation are separated in time and space:
transcription can only happen inside the nucleus while translation takes place in the
cytoplasm or endoplasmic reticulum. Because prokaryotes do not have a membrane
enclosing their DNA, DNA replication machinery, RNA polymerase, and ribosomes can
all access the DNA/RNA at the same time and place.
Which measure of bacterial density does not distinguish between live and dead cells?
A. A viable count assay
B. Turbidity measurement with a spectrophotometer
C. Counting the cells in a counting chamber device by phase contrast microscopy
D. A and B
E. B and C - Answers -E. B & C
Which of the following are NOT influenced by cell size:
A. Type of microscopy used to image cells
B.Acquisition of nutrients from the environment
C. Microbial growth rate (how quickly they replicate)
D. Surface area/volume ratio
E. Presence of a phospholipid membrane - Answers -E. Presence of a phospholipid
membrane
All organisms have this
Which statement provides evidence that the Eukarya lineage arose by the "ingestion" of
an ancestral bacterium by an ancestral archaeaon (cell from Archaea lineage)?
A. All eukaryotic organisms produce O2
B. Eukaryotic DNA replication and transcription enzymes are most similar to the the
equivalent enzymes in modern Archaea
C. Modern day Archaea have been observed to ingest Bacteria
D. Mitochondria resemble modern cyanobacteria in appearance and metabolism
E. Chloroplasts have a larger genome than modern cyanobacteria - Answers -B.
Eukaryotic DNA replication and transcription enzymes are most similar to the the
equivalent enzymes in modern Archaea
Because the DNA replication and transcriptional machinery of eukaryotic cells is most
similar to the equivalent enzymes in Archaea, and mitochondrial genes most closely
resemble equivalent genes found in Bacteria, it is thought that an archaeaon engulfed a
bacterium. This endosymbiont became fixed and degraded over time into an organelle,
the mitochondrion.
True or False
All cellular organisms grow best at 37C although some extremophiles can tolerate much
higher or lower temperatures. - Answers -False
Extremophiles are highly adapted to the environments they are found in and would find
"normal" human temperatures incompatible with survival and/or growth.
Which molecule is NOT a constituent of the gram-negative bacterial envelope?
A. Lipopolysaccharide
B. Periplasm
C. Lipoteichoic acid
D. Peptidoglycan
E. C and D - Answers -C. Lipoteichoic acid
,Note: Lipoteichoic acid is the true answer, but because the textbook had not yet defined
"peptidoglycan", I will accept peptidoglycan as well. Due to limitations in Canvas, the
only way I can give credit for answers C, D, and C and D is to give all students credit for
the question.
Lipopolysaccharide and the periplasm are found only in gram-negative cells.
Peptidoglycan is found in (nearly) all Bacteria, although gram-positive cells have
significantly more layers of this "cell wall" material. Lipoteichoic acid (and wall teichoic
acid) acid are found only in the envelope of gram-positive cells.
True or False
All microscopes use light or electrons to image cellular structures. - Answers -False
Scanning probe microscopes use a metal tip to probe the contours and properties of
surface structures.
Which type of cell is most susceptible to osmotic lysis in an environment with a very low
concentration of solutes (hypotonic)?
A. Gram-negative cell
B. Gram-positive cell
C. Mycoplasma
D. Acid-fast mycobacterium
E. Archaeon with pseudomurein - Answers -C. Mycoplasma
p35-45 Mycoplasma are the only prokaryotic group listed that do not have a cell wall to
resist high osmotic pressure caused by water moving into the solute-rich cell. While
Mycoplasma are highly successful inside the relatively isotonic environment inside a
host's body, they do not fare well in hypotonic environments or even tissue culture.
Which of the following cellular structures self-assemble (i.e. purified monomers can
assemble into the structure without added factors or the input of energy)?
A. Flagellar filament
B. Phospholipid bilayer
C. Pili
D. S layer
E. A and B
F. C and D
G. A, B, & C - Answers -G. Flagellar filament, Phospholipid Bilayer, Pili
p49-51 Pili are built of monomers of the protein pilin that are added to the base of the
pilus filament. Flagellin aggregates spontaneously at the tip of the flagellar filament
during flagellar assembly. p44 The S-layer is a lattice of a single protein that will self-
assemble into highly-ordered arrays.
What distinguishes an organelle from a carboxysome or enterosome?
, A. Organelles contain DNA
B. The function of organelles is to compartmentalize metabolic activities
C. Carboxysomes and enterosomes are enclosed within a membrane
D. A and B
E. A, B, and C - Answers -A. Organelles contain DNA
p71-74 Carboxysomes and enterosomes are protein-enclosed compartments where
bacteria concentrate the enzymes and substrates for carbon fixation or propanediol and
ethanolamine metabolism, respectively. There is no evidence to suggest they are
derived from an ancient endosymbiont—such as chloroplasts and mitochondria are
thought to be—including the absence of a (much reduced) genome.
DNA may be observed in which form inside of Bacterial cells?
A. Circular chromosomes
B. Linear plasmids
C. Bound by DNA-condensing RNA molecules
D. Attached to high concentrations of anions - Answers -A. Circular chromosomes
p64-68 Most Bacteria have a single circular chromosome bound by DNA-condensing
proteins (much like the histones that organize eukaryotic DNA). Positively-charged
cations in the cytoplasm reduce the electrostatic repulsion of negatively-charged DNA
and allow its condensation into higher-ordered loops and supercoiled structures.
Bacteria may also have circular plasmids, which encode functions not essential for
survival (note: a cell may be "cured" of a plasmid but never of a chromosome).
True or False
Only prokaryotes can transcribe and translate a gene at the same time. - Answers -
True
True
In eukaryotes, transcription and translation are separated in time and space:
transcription can only happen inside the nucleus while translation takes place in the
cytoplasm or endoplasmic reticulum. Because prokaryotes do not have a membrane
enclosing their DNA, DNA replication machinery, RNA polymerase, and ribosomes can
all access the DNA/RNA at the same time and place.
Which measure of bacterial density does not distinguish between live and dead cells?
A. A viable count assay
B. Turbidity measurement with a spectrophotometer
C. Counting the cells in a counting chamber device by phase contrast microscopy
D. A and B
E. B and C - Answers -E. B & C
