WGU C453 Clinical Microbiology Exam
guide Questions and Answers Graded A+
Bacteria - Correct answer-Single-celled organism that do not have a cell nucleus
and the membrane-enclosed intracellular structures found in most other cells
(Prokaryotic cell).
Gram-positive Bacteria - Correct answer-Thick layer of peptidoglycan (20-80nm
across). The peptidoglycan layer is closely attached to the outer surface of the cell
membrane. Retains crystal violet stains. Lack an outer membrane and a
periplasmic space.
Gram-negative Bacteria - Correct answer-Cell wall is thinner, but more complex.
Only 10-20% peptidoglycan. Contains an outer membrane, leaving a very narrow
periplasmic space. Does not retain crystal violet stain because of large quantities of
lipoproteins and lipopolysaccharides (endotoxin).
Acid-fast Bacteria - Correct answer-Cell wall is thick, but consists of 60% lipids.
Lipids make acid-fast organisms impermeable to most other stains and protect
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,them from acids and alkalis. Stain as gram-positive. Grow slowly because the
lipids impeded entry of nutrients.
Endotoxin - Correct answer-Lipopolysaccharide (LPS). Part of the outer membrane
of the cell wall of gram-negative bacteria. It can cause fever and dilates blood
vessels- causing BP to drop. Bacteria typically release this when they are dying, so
killing them increases the concentration of this toxic substance. Antibiotics given
late in the infection can cause worsening of symptoms or even death.
Wall-deficient Bacteria - Correct answer-Protected by a strengthened cell
membrane that contains sterols. Example: mycobacterium paratuberculosis with
Crohn's disease- a chronic disorder of the intestine.
Coccus - Correct answer-Sphere shaped bacteria
Coccobacillus - Correct answer-Short rod shaped bacteria (between cocci and
bacilli)
Vibrio - Correct answer-Comma shaped bacteria
Bacillus - Correct answer-Rod shaped bacteria
Spirillum - Correct answer-Rigid, wavy shaped bacteria
Spirochete - Correct answer-Corkscrew shape bacteria
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, Function of cell membrane - Correct answer-To regulate movement of materials
into and out of the cell by transport mechanisms. It synthesizes cell wall
components, assists with DNA replication, secretes proteins, carries on respiration,
and captures energy as ATP.
Function of the cell wall - Correct answer-Helps maintain the characteristic shape
of the cell and prevents the cell from bursting when fluids flow into the cell by
osmosis. Lies outside the cell membrane.
Peptidoglycan - Correct answer-Single most important component of the bacterial
cell wall.
Capsule - Correct answer-Discrete layer of polysaccharides that protects the cell.
Promotes infection by protecting the bacterial cell from engulfment by predatory
protozoa or WBC (phagocytes). Also mediates adherence of cells to surfaces.
Pili - Correct answer-Tiny, hallow projections that are used to attach bacteria to
surfaces. Are NOT involved in movement. Promote infection by transferring DNA
amount bacteria- which in turn can transfer antibiotic resistance. Can adhere to
RBC and cause blood cells to clump.
Flagella - Correct answer-Long, thin, helical appendages that allow bacteria to
move.
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guide Questions and Answers Graded A+
Bacteria - Correct answer-Single-celled organism that do not have a cell nucleus
and the membrane-enclosed intracellular structures found in most other cells
(Prokaryotic cell).
Gram-positive Bacteria - Correct answer-Thick layer of peptidoglycan (20-80nm
across). The peptidoglycan layer is closely attached to the outer surface of the cell
membrane. Retains crystal violet stains. Lack an outer membrane and a
periplasmic space.
Gram-negative Bacteria - Correct answer-Cell wall is thinner, but more complex.
Only 10-20% peptidoglycan. Contains an outer membrane, leaving a very narrow
periplasmic space. Does not retain crystal violet stain because of large quantities of
lipoproteins and lipopolysaccharides (endotoxin).
Acid-fast Bacteria - Correct answer-Cell wall is thick, but consists of 60% lipids.
Lipids make acid-fast organisms impermeable to most other stains and protect
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,them from acids and alkalis. Stain as gram-positive. Grow slowly because the
lipids impeded entry of nutrients.
Endotoxin - Correct answer-Lipopolysaccharide (LPS). Part of the outer membrane
of the cell wall of gram-negative bacteria. It can cause fever and dilates blood
vessels- causing BP to drop. Bacteria typically release this when they are dying, so
killing them increases the concentration of this toxic substance. Antibiotics given
late in the infection can cause worsening of symptoms or even death.
Wall-deficient Bacteria - Correct answer-Protected by a strengthened cell
membrane that contains sterols. Example: mycobacterium paratuberculosis with
Crohn's disease- a chronic disorder of the intestine.
Coccus - Correct answer-Sphere shaped bacteria
Coccobacillus - Correct answer-Short rod shaped bacteria (between cocci and
bacilli)
Vibrio - Correct answer-Comma shaped bacteria
Bacillus - Correct answer-Rod shaped bacteria
Spirillum - Correct answer-Rigid, wavy shaped bacteria
Spirochete - Correct answer-Corkscrew shape bacteria
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, Function of cell membrane - Correct answer-To regulate movement of materials
into and out of the cell by transport mechanisms. It synthesizes cell wall
components, assists with DNA replication, secretes proteins, carries on respiration,
and captures energy as ATP.
Function of the cell wall - Correct answer-Helps maintain the characteristic shape
of the cell and prevents the cell from bursting when fluids flow into the cell by
osmosis. Lies outside the cell membrane.
Peptidoglycan - Correct answer-Single most important component of the bacterial
cell wall.
Capsule - Correct answer-Discrete layer of polysaccharides that protects the cell.
Promotes infection by protecting the bacterial cell from engulfment by predatory
protozoa or WBC (phagocytes). Also mediates adherence of cells to surfaces.
Pili - Correct answer-Tiny, hallow projections that are used to attach bacteria to
surfaces. Are NOT involved in movement. Promote infection by transferring DNA
amount bacteria- which in turn can transfer antibiotic resistance. Can adhere to
RBC and cause blood cells to clump.
Flagella - Correct answer-Long, thin, helical appendages that allow bacteria to
move.
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