C453 V5 Clinical Microbiology Study Questions and
answers (from module 1-19) 2024 Western Governors
University
Bacteria - answers 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 - answers 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 - answers 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 - answers 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 - answers 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 - answers Protected by a strengthened cell membrane that
contains sterols. Example: mycobacterium paratuberculosis with Crohn's disease- a
chronic disorder of the intestine.
Coccus - answers Sphere shaped bacteria
Coccobacillus - answers Short rod shaped bacteria (between cocci and bacilli)
Vibrio - answers Comma shaped bacteria
Bacillus - answers Rod shaped bacteria
Spirillum - answers Rigid, wavy shaped bacteria
Spirochete - answers Corkscrew shape bacteria
Function of cell membrane - answers 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.
, C453 V5 Clinical Microbiology Study Questions and
answers (from module 1-19) 2024 Western Governors
University
Function of the cell wall - answers 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 - answers Single most important component of the bacterial cell wall.
Capsule - answers 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 - answers 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 - answers Long, thin, helical appendages that allow bacteria to move.
Endospore - answers 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 - answers Process of bacteria moving toward or away from substances
in their environment. Towards- positive, Away- Negative.
Bacteria that produce spores - answers Bacillus, Clostridium
Helminths - answers Worm-like organisms living in and feeding on live hosts,
receiving nourishment and protection while disrupting their hosts' nutrient absorption,
causing weakness and disease. Example: Flukes, tapeworms, adult round-worms of
intestine, and roundworm larvae.
Zygomycota - answers Bread molds
Ascomycota - answers Sac fungi. Yeasts. Replication by sexual reproduction.
Basidiomycota - answers Club fungi. Amanita and other mushrooms.
Virus - answers Tiny, non living particle that invades and then reproduces inside a
living cell. Contain only one kind of nucleic acid- either DNA or RNA (never both).
Naked virus - answers Virus with only a nucleocapsid and no envelope.
Enveloped virus - answers Have a bilayer membrane outside their capsids.
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