M4: Bacteria II Flashcards
Doubling times are faster for (prokaryotes/eukaryotes) than for (prokaryotes/eukaryotes)
prokaryotes
eukaryotes
Bacterial growth is often studied in vitro: Cultivation methods (2)
solid media
broth media
Bacterial growth is often studied in vitro:
Cultivation methods:
Solid media: useful for obtaining _ cultures by _
Broth media: can be used to propagate a _ culture using “_ technique”
“pure”
streak-plating
pure
aseptic
Bacterial growth is often studied in vitro:
To measure bacterial growth, you can evaluate either:
_ bacteria in a culture (measure _ with a _)
_ bacteria in a culture (count _ on plates, after sample _)
Total
turbidity
spectrophotometer
Viable
colonies
dilution
A typical bacterial growth curve:
Stages (4)
Lag
Exponential
Stationary
Total / Viable
A typical bacterial growth curve:
Lag
Exponential
Stationary
Total / Viable
preparing to grow
growth, doubling time
almost all bacteria are alive & viable
viable is less than total #
Important factors for bacterial growth: (5)
temperature pH oxygen (redox) concentrations nutrients (e.g. iron) osmolarity
Bacterial growth in vivo vs. in vitro
In vitro studies provide an inexact model for understanding bacterial growth in vivo
Bacterial Physiology and Pathogenesis:
Some host defenses are targeted at bacterial physiology
For example, the body uses _ proteins (_ and _) to restrict the availability of iron for
pathogens
However, pathogens can fight back:
a. By producing their own _ molecules (e.g. _)
b. Some bacteria (e.g. the pathogenic _) can bind human _ and _ to their surface and then use that bound iron.
iron-binding
lactoferrin and transferrin
iron-binding
siderophores
Neisseria spp.
lactoferrin and transferrin
Bacterial Physiology and Pathogenesis:
_ is key for growth of bacterial pathogens.
These organisms obtain it by:
_: uses an _ substance (e.g. O2) as the terminal electron acceptor
_: uses an _ substance as the terminal electron acceptor
_, e.g., _ and _
There is, usually, a relationship between _ and bacterial _
Energy
Respiration
inorganic
Fermentation
organic
Intracellular energy theft
Chlamydiae and Rickettsiae
energy production
growth rates
Aerobes
e.g.
grow only in the presence of O2
e.g. Pseudomonas aeruginosa
Microaerophiles
e.g.
a special group of aerobes requiring O2, but at lower concentrations than found in normal air
e.g. Campylobacter spp.
Facultative anaerobes
grow by _, but shift their metabolism to _
More ATP is produced during (fermentation/respiration) than (fermentation/respiration), so growth is faster here
e.g.
grow in either the presence or absence of O2
fermentations in the absence of O2
respiration in the presence of O2
respiration
fermentation
e.g. E. coli
Aerotolerants
e.g.
grow in presence or absence of O2, but metabolism always uses fermentation
most Streptococcus spp.
Strict anaerobes
e.g.
grow only in the absence of O2
e.g. Clostridium spp
Why some bacteria are anaerobic:
Anaerobes often lack _ (which breaks down _ formed after cells are exposed to _).
Anaerobes often lack _ (which detoxifies free radical forms of _ that form after cells are exposed to _).
Anaerobes may have very sensitive _ that require a _ environment.
Bottom line: anaerobes must be in a _ environment and O2 (raises/lowers) the _.
catalase
toxic H2O2
air
superoxide dismutase
O2
air
enzymes
reduced
low redox (reduced) raises redox potential
The redox potential of healthy tissue is too (high/low) for anaerobes to grow.
However, a number of medical conditions can (raise/lower) tissue redox potential: (3)
high
lower
a. Circulatory problems (from heart disease, etc).
b. Tight orthopedic casts.
c. The co-presence of facultative anaerobes (which can consume oxygen) during an infection.
Anaerobes are often present as _ in many locations in the healthy human body:
a. _: e.g. _
b. _: e.g. _
c. _: e.g. _; _
d. _: e.g. _
normal flora
a. Skin: e.g. Propionibacterium spp.
b. Mouth: e.g. Porphyromonas gingivalis
c. Vagina: e.g. Lactobacillus spp.; Prevotella bivia
d. Colon: e.g. Bacteroides fragilis
Gram-positive anaerobes of medical importance:
Sporeforming rods: _
Non-sporeforming rods: _
Cocci: _, _
Clostridium spp.
Actinomyces spp.
Peptococcus, Peptostreptococcus spp.
