L3, L5, L7- Microbiome and Biology of Gram +/- Bacteria Flashcards
___________ bacteria are commonly ubiquitous on the skin
Staphylococcus
microbiota are also known as….
commensal flora
very high numbers of bacteria are found in the mouth and large intestine, especially…
Escherichia coli
microbiota are importantly absent in (1) or (2) locations (include examples)
1- non-epithelial
2- mucosal
ex. blood, CSF
_______ is a common opportunistic gut infection that follows from the death of numerous gut flora due to antibiotic use
C. diff (clostridium difficile)
list 4 general characteristics of microbiome
- protection against disease
- important for barrier and immune modulation
- influences host metabolism and drug interaction
- possible source of infection (endogenous E.coli in Colon)
define dysbiosis and its effects
this is usually a transient effect resulting from long-term or repeated antibiotic use leading to the loss of beneficial species, altering microbiota
associated with chronic diseases like Crohn’s or IBS
describe prokaryotic DNA
circular, ~1 mil. BPs + many Plasmids with ~50k BPs
breakdown prokaryotic vs eukaryotic ribosomes
Pro: 30S + 50S = 70S
Euk: 40S + 60S = 80S
plasmids in bacteria contain DNA coding for….
- antibiotic resistance
- toxins
- mobile gene transfer
list in order the stages of bacterial growth
1) lag phase
2) log / exponential phase
3) stationary phase
4) death phase
describe the features of Lag phase
- newly inoculated cells, adjust to environment (is there food, space, etc)
- cells not multiplying at maximum rate
- population is sparse or dilute
describe the features of Log or exponential phase
- growth occurs at exponential rate and cells are at maximal rate of cell division
- continues as long as environment is favorable (nutrients present, etc)
describe features of stationary phase
- population at maximum number
- rate of cell inhibition/death = rate of cell multiplication
- accumulation of toxic waste products
describe features of death phase
- decline in growth rate
- caused by depletion in nutrients, O2
- excretion of toxic waste products
- increased density of cells (limited space)
describe how and why bacteria obtain Fe
- Fe is required for cytochromes
- most Fe is sequestered in Hb, therefore bacteria must have mechanisms to extract Fe from Hb
list the three ways bacteria generate ATP
- aerobic respiration
- anaerobic respiration
- fermentation
_______ levels are usually measured in urine samples to serve as an indicator of infection since the humans cannot break it down
nitrates (E.coli can convert it to nitrites)
if bacteria deplete enough O2 during an infection, the anoxic conditions can lead to….
- host tissue damage
- immune cells work poorly
- antimicrobials are less effective
most pathogens have an optimal temperature of growth at (1) and are referred to as (2)
1- 37C
2- mesophiles
define obligate aerobe
O2 necessary, only aerobic respiration is used (die w/o O2)
define obligate anaerobe
can’t use O2 and die in its presence
define facultative anaerobe
uses both aerobic and anaerobic respiration, although thrive more in aerobic conditions
define microaerophiles
require lesser amounts of O2 (5-10%)