Bacterial structure Flashcards
lag phase
no increase in cell number due to adaptation
log (exponential phase)
active and uniform growth
Stationary phase
growth and death balance because food runs out which makes peptides signal to stop growing
Death phase
cells die rapidly
clinical significance of stationary phase?
stationary phase cells are resistant to some cell wall antibiotics
what are the nutritional requirements for heterotrophic bacteria?
requires organic matter like glucose, carbon source, and oxidative phosphorylation
minimal defined and undefined media is for ?
clinic (diagnosis) and research
what is glycocalyx?
capsules and biofilms
capsules used for antiphagocytosis
biofilms and slime used for immune surveillance and antibiotic resistance by preventing it from penetrating
what are important virulent factors?
capsules
what are nucleoids?
(in prokaryotes where all genetic material is contained)
double stranded circular DNA molecule
not bounded by membranes
bacterial chromosomes are condensed into supercoiled loop domains
what are plasmids?
autonomously replicating circular DNA
antibiotic resistance, produces toxins
takes effect by bacterial conjugation
what are ribosomes?
synthesizes proteins
are large, 80 protein - RNA complexes
prokaryotic ribosomes are smaller than eukaryotic ribosomes and are sensitive to antibiotics that do not affect eukaryotic ribosomes
which factors influence bacterial growth?
pH- (acidophiles, neutrophiles, or alkaliphiles)
atmosphere- (anaerobes, aerobes, or facultative anaerobes)
Temperature - (flora of human body)
Osmolarity - (halophilic - high [salt] or osmophilic- high osmotic pressure)
what is the growth rate of TB?
what is the growth rate of pseudomonas?
TB is slow growing 12 hours doubling time
Pseudomonas is fast growing 20 min doubling time
why is it good to be a non-enveloped virus?
because No drying! resistant to drying
what are the 3 mechanisms in bacteria for genetic variability?
conjugation - cell to cell contact to transfer genes
transformation - uptake of DNA from medium
transduction - bacteriophage mediated gene transfer
why are endospores a virulence factor?
because they are heat resistant due to Ca-dipicolinate
Transposons
are “jumping genes” that can move within or between genomes
what are the two mechanisms of genetic variability?
which is important for pathogenesis and antibiotic resistance
mutagenesis - heritable change in nucleic acid sequence
Horizontal gene transfer - transfer of genetic material btw organisms of same or different species
whats sepsis?
hosts response to gram negative LPS (Lipid A)
what is bacteremia caused by sepsis?
bacteria in the blood stream
