Bacteriology Flashcards
describe the general process of recombinant bacteria insulin manufacture
isolate plasmid and human DNA
cut both DNA with same restriction enzymes
mix DNA - get recombinant and no recombinant plasmids
introduce the DNA into bacterial cells that have mutation in own lacZ gene
two general ways bacteria cause disease
give a couple examples
disrupting the physiology of the cell by invasion and growth (leprosy, syphilis, typhoid fever)
growing inside the host and producing toxins (tetanus, botulism)
how many bacterial cells does the human body contain
10^14
what pathogens can resident E.coil in the gut kill
salmonella, shigella, clostridium (by producing compounds that kill them)
what phylogenetic analysis is used to distinguish between bacterial species
16S rRNA analysis by PCR - gene amplified by the Sanger method
why is the 16S rRNA sequence used to distinguish between dna
high copy number, variable and conserved regions, essential for life
what are the two main types of bacteria
Gram positive - blue, thick layer of peptidoglycan
Gram negative - pink, thin layer of peptidoglycan
what factors influence speciation in bacteria
- relatively fast generation times
- adaptive mutations
- horizontal gene transfer and the ‘core’ genome
what are the 3 routes of horizontal gene transfer
- transformation - naked DNA released by one cell and taken up by another
- transduction- bacterial DNA begin transfer by virus, by phages
- conjugation - cells join together and DNA can transfer from one to the other
what is the pan genome
include the other mobile genetic elements, those coming in from outside
what is the core genome
part of genome present in all strains of a species
what are the agents of horizontal gene transfer
prophages and plasmids
what are biofilms characterised by
3
irreversibly attached to a substratum interface or each other
are embedded in a self produced matrix of EPS
exhibit an altered phenotype (compared w planktonic cells) with respect to: growth rate and gene transcription
what are the 6 stages of biofilm lifecycle
- reversible adhesion
- irreversible attachment
- maturation
- development
- dispersion and sloughing off
- transport of biofilm particles
what components make up the EPS
biopolymers: polysaccharides, proteins, glycoproteins, phospholipids, nucleic acids
what structures allow for irreversible adhesion/ polymer bridging give 4 (of9)
exopolymers fimbriae flagella stalks lipoteichoic acids LTA lipopolysaccharides LPS s layers a layers surface localised proteins and pigments
what are the three main functions of the cytoplasmic membrane
selective permeability
transport
energy conservation &consumption (proton motive force)
what types of motility are exhibited by bacteria
Flagellar, Spirochaetal, Gliding
bacterial flagella are around _____ thick and contain the protein ________
20nm thick and contain flagellin
what six ways can bacteria move
swimming - rotating flagella
gliding - active surface movement involving focal adhesion complexes
twitching - jerk from attachment and detachment of type IV pili
swarming - multicellular surface movement by rotating helical flagella
sliding - passive surface translocation
darting -rapid motion
what five ways can flagella be arranged on bacterium
Atrichous - no flagellum
Monotrichous - single flagellum
Lophotrichous - multiple flagella from the same location, forming a ‘tuft’
Amphitrichous - a single flagellum at each end
Peritrichous - numerous flagella around the cell (random array)
what are the two main types of pili
conjugation pili
type IV pili
describe the process of bacterial conjugation
1 donor cell produces pilus
2 pilus attaches to recipient cell, brings two cells together
3 the mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell
4 both cells recircularise their plasmids, synthesise second strands and reproduce pili: both are now viable donors
