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Bacteria cell structure & metabolism
medical microbiology
49
Medical
Professional
08/23/2011

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Term
distinguishing factors of a prokaryote?
Definition
no nuclear membrane
no organelles
Term
how can bacteria transfer virulence genes withing and between species?
Definition
plasmids (self replicating DNA)
Term
what propels the flagella?
Definition
Ion motive force (not a virulence factor)
Term
describe the flagella of monotrichous
Definition
single polar flagellum
Term
describe the flagella of amphitrichous
Definition
flagella at both poles
Term
describe the flagella of lophotrichous
Definition
a cluster of flagella at one pole
Term
describe the flagella of peritrichous
Definition
glagella encircling the cell
Term
which direction does a flagellum grow?
Definition
from the tip, not the base
Term
what is chemotaxis?
Definition
a bacteria swimming up a concentration gradient. VIRULENCE FACTOR
Term
what type of bacteria most often has pili and fimbriae?
Definition
Gram-negative
Term
what is the function of 'F' or 'sex' pili?
Definition
To transfer DNA to others cells (conjunction). It's longer and thicker than other types.
Also, its a receptor for bacteriophages which are viruses that can infect bacteria
Term
are pili and fimbrae virulence factors of bacteria?
Definition
Yes
Term
what is the difference between a capsule and glycocalyx?
Definition
capsules are uniform and condensed around the cell while glycocalyx forms a loose meshwork of fibrils that extend outward from the cell
Term
Why are capsules a virulence factor?
Definition
resist changes in osmolarity (high salt/low salt) and protect against phagocytosis
Term
why is E. coli able to be engulfed while streptococcus isn't?
Definition
Strep has a capsule
Term
what is the function of the cell wall?
Definition
provides shape and resistance to osmotic pressure differences between the environment and cytoplasm
Term
why must Mollicutes live in a resticted envirment where the osmlarity doesn't change?
Definition
They don't have a cell wall
(not affect by penicullin bc no cell wall)
Term
what color do gram-positive cells stain?
Definition
blue
Term
what is the difference between gram-positive and negative bacteria?
Definition
The cell wall
postive have a thick outer wall with no lipids while gram-negative have a thin wall and outer membrane
Term
alcohol/acetone washes away anything attached to the outer membrane of what type of bacteria?
Definition
Gram-negative
Term
what is the protcol for a gram stain?
Definition
1. Heat fix
2. Cyrstal violet
3. Iodine
4. De-colrize
5. Counter stain
Term
what's the function of the cell envelope?
Definition
protect cell against environmental changes (osmotic pressure)
Term
what makes of the cell wall?
Definition
peptidoglycan
Term
what is the difference between gram negative and postive bacteria regarding their peptidogylcan layer?
Definition
Negative only has 1 layer (but it's got a outer membrane)
postive has 15-20 layers
Term
why are gram-postive cells more resistant to dry locations?
Definition
thicker peptidoglycan layer, but this also makes them more suseptible to penicillin
Term
what amino acid of found in the tetrapeptides of gram-negative bacteria?
Definition
diamonophimelic acid
Term
what amino acid of found in the tetrapeptides (cross linking) of gram-positive bacteria?
Definition
lysine
(except staphlococcus aerues has glycine)
Term
what type of bacteria would have techoic acid in their cell wall? and whats it's function?
Definition
gram-positive bacteria

techoic acid is negatively charged so it attracts Mg2+ Ca2+ and can bind to protons which lowers the walls pH and decreases rate of degredation by autolysins
Term
what bacteria type has lipoproteins?
Definition
gram-negative
Term
why is the outer membrane of gram-negative bacteria more permeable to small molecules than the cytoplasmic membrane?
Definition
the outer membrane has porins
Term
which layer of gram-negative bacteria is more permeable to hydrophobic (nonpolar) and amphipathic molecules?
Definition
the cytoplasmic membrane is more permeable
Term
where are lipopolysaccharides found?
Definition
the outer layer of the outer membrane of gram-negative bacteria
Term
what is clinically important about LPS?
Definition
its acts as a endotoxin and VIRULENCE factor
Term
whats the function of O-antigen found in LPS?
Definition
VIRULENCE factor for escapting phagocytosis
Term
why can't hydrophobic molecules cross the outer membrane of gram negative bacteria?
Definition
LPS molecules are - and attract divalent cations (Mg2+ and Ca2+)
Term
what is the toxic protion of LPS?
Definition
Lipid A
(LPS molecule introduced into animal cause fever and even death)
Term
where can you find lysozyme?
Definition
tears and saliva
Term
how does penicillin inhibit cell wall synthesis?
Definition
it forms an inactive complex with transpeptidase so cross-bridges can't from
Term
what is an endospore?
Definition
produced from Bacillus or Clostridum and are resistant to extreme heat.
Term
what's the function of calcium dipicolinate in an endospore?
Definition
to stablize its core
Term
define facultative aerobes
Definition
can live with or without oxygen, derive ATP aerobically or anaerobically
Term
define obligate anaerobes
Definition
require oxygen, derive ATP from proton motive force from electron transport chain with oxygen as terminal electron receptor
Term
define anaerobes
Definition
can't use oxygen as energy source, derive energy from fermentation
Term
what is anaerobic respiration?
Definition
when the electron transport uses fumarate or nitrate instead of oxygen and the final electron acceptor (still generates more energy than fermentation)
Term
why is it important to re-oxidize NADPH at the end of fermentation?
Definition
if NADPH builds up in inhibits glycolysis leading to decreased ATP synethsis
Term
what limits the exponential growth of bacteria?
Definition
lack of nutrients and energy
Term
what are the 4 stages of bacterial growth?
Definition
1. lag phase
2. exponential phase
3. stationary phase
4. death phase
Term
what happens during the lag phase of bacterial growth?
Definition
cell in increasing in size and synsthesizing DNA and RNA but not dividing
Term
what is the formula for cell number?
Definition
cell number = 2^n (n equels number of generations)
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