WGU C453 Clinical Microbiology
Bacteria - 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 - 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 - 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 - ANSWER: Cell wall is thick, but consists of 60% lipids. Lipids make acid-fast organisms
impermeable to most other stains and protect them from acids and alkalis. Stain as gram-positive. Grow
slowly because the lipids impeded entry of nutrients.
Endotoxin - 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 - ANSWER: Protected by a strengthened cell membrane that contains sterols. Example:
mycobacterium paratuberculosis with Crohn's disease- a chronic disorder of the intestine.
Coccus - ANSWER: Sphere shaped bacteria
Coccobacillus - ANSWER: Short rod shaped bacteria (between cocci and bacilli)
Vibrio - ANSWER: Comma shaped bacteria
Bacillus - ANSWER: Rod shaped bacteria
, Spirillum - ANSWER: Rigid, wavy shaped bacteria
Spirochete - ANSWER: Corkscrew shape bacteria
Function of cell membrane - 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 - 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 - ANSWER: Single most important component of the bacterial cell wall.
Capsule - 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 - 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 - ANSWER: Long, thin, helical appendages that allow bacteria to move.
Endospore - ANSWER: Helps the organism survive, and is not a means of reproduction. They are formed within
the cells, contain very little water and are highly resistant to heat, drying, acids, bases, certain disinfectants,
and even radiation. They are capable of surviving adverse environmental conditions for long periods of time.
Chemotaxis - ANSWER: Process of bacteria moving toward or away from substances in their environment.
Towards- positive, Away- Negative.
Bacteria that produce spores - ANSWER: Bacillus, Clostridium
Bacteria - 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 - 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 - 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 - ANSWER: Cell wall is thick, but consists of 60% lipids. Lipids make acid-fast organisms
impermeable to most other stains and protect them from acids and alkalis. Stain as gram-positive. Grow
slowly because the lipids impeded entry of nutrients.
Endotoxin - 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 - ANSWER: Protected by a strengthened cell membrane that contains sterols. Example:
mycobacterium paratuberculosis with Crohn's disease- a chronic disorder of the intestine.
Coccus - ANSWER: Sphere shaped bacteria
Coccobacillus - ANSWER: Short rod shaped bacteria (between cocci and bacilli)
Vibrio - ANSWER: Comma shaped bacteria
Bacillus - ANSWER: Rod shaped bacteria
, Spirillum - ANSWER: Rigid, wavy shaped bacteria
Spirochete - ANSWER: Corkscrew shape bacteria
Function of cell membrane - 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 - 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 - ANSWER: Single most important component of the bacterial cell wall.
Capsule - 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 - 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 - ANSWER: Long, thin, helical appendages that allow bacteria to move.
Endospore - ANSWER: Helps the organism survive, and is not a means of reproduction. They are formed within
the cells, contain very little water and are highly resistant to heat, drying, acids, bases, certain disinfectants,
and even radiation. They are capable of surviving adverse environmental conditions for long periods of time.
Chemotaxis - ANSWER: Process of bacteria moving toward or away from substances in their environment.
Towards- positive, Away- Negative.
Bacteria that produce spores - ANSWER: Bacillus, Clostridium
