microbiology Flashcards
Define competitive exclusion
where co-occurring bacteria with the same niche compete for limited resources
Describe how PCR works ? - including three main processes
melting
annealing
synthesis
- reaction mix heated 95C , hydrogen bonds of DNA nucleotides broken down . Double stranded DNA will be denatured
- reaction mix cooled down to annealing temp , primers align with complimentary sequence of the target DNA - form hydrogen bonds
3, reaction mix heated optimum temp for dna polymerase which extends the primers 5’ to 3’ direction , cycle starts again
How is PCR used in diagnosis ?
-directly detects pathogen DNA
-used to confirm clinical disease , current infection or cause of death
-only useful if applied early stages as detects pathogen directly
list and breifly describe the main mutations
-silent - substitute one nucleotide - no change aa
-missense - sub nucleotide - change aa
-point - change codon for aa into stop codon
-insertion - addition of nucleotide(s)
-deletion - removal nucleotide (s)
what does negative control do ?
minimise effect of external variables
Define Genome
an organisms entire DNA - genes ( coding regions ) and non coding regions
what does positive control do ?
allows you to make sure all your equipment is working properly . Making sure that the experiment can have a positive outcome.
What factors can alter gut microflora ?
meds
stress
diet
genetics
co-concurrent infection
Outline key features of enteric viruses
-infectious does small
-short incubation and is lytic - cause damage and acute
-large amounts shed in faeces
-tough - survive low ph of stomach and environment
-2ndary infection is common
-diarrhoea common
-death from dehydration
-denudation of microvilli - shortening ,flattening ( malabsorption )
How do viruses enter cells ?
bind to sialic acid — integrins — other proteins on cell surface
Define mitochondrial genome
single circular chromosome that encodes some proteins necessary for mitochondrial function
Define microbiome
is the combined genetic material of the microorganisms in a particular environment
What is the role of microbiome ? where does it differ
-shows host and theyre biology and allows you to detect changes in this
-see whats already there
-compare hosts of different health
-different micro-environments ,age ,external factors e.g antibiotics
define role of microbiome in gut health and disease
-diversity and abundance of microbiome - effect energy balance , gut motility , inflammatory tone , mucosal integrity ,appetite and signalling
-pathogens introduced - gut promote inflammation disrupts microbiota
-gut microbiota can also influence brain development , neural process and behaviour - metabolites can cause anxiety, memory , social , feeding behaviour
How can you analyse genomes and microbiomes ?
PCR ,sequencing , Multi locus sequence typing MLST
How does sequencing work ?
-7 housekeeping genes
- each strain given alleic profile
-if sequence different considered new allele and given unique allele number
-each different alleic profile is given a one digit sequence type
How is sequencing different from MLST?
-MLST uses whole genome
Outline transcription and translation
transcription - DNA - RNA
translation - RNA - protein
struc and func of bacterial chromosomes and plasmids
chromosome haploid circular DNA , organised into complex called nucleoid - carry whole genome
plasmid - independent small DNA molecule which can replicate independently – helps with division and can transfer properties between bacteria
How do bacteria transfer genes between each other ?
-transformation - uptake of naked DNA , either degraded by nucleases or recombines into genome
-conjugation - horizontal gene transfer , transfer dna via direct cell to cell contact( donor to recipient ) , donor needs to have plasmid or transposon ( mobile or conjugative gene element
-transduction recombination - by bacteriophage
lytic ( generalised ) or temperate ( specialised
describe lytic transduction
-attach
-infect /inject
-lag phase - replication
-lyse - during lysis DNA can be packaged by mistake
explain temperate phage transduction
- bacteriophage attach to bacteria cell - lysogen
- bacteriophage fuse with baceria cells genome to form prophage
-replication
-bacteria cells dna packaged into bacteriophage
-when bacteriophage infects another cell its DNA combines with the infected bacterial cells genome
What are restriction endonucleases ?
they restrict the bacteria cell from constantly taking up DNA by degrading DNA not made in there own cell
What is the struc and func of transposon ?
a transposon is a sequence of DNA
they encode they’re own transposases that cut out and re-insert the DNA marked by inverted repeats
=transposition
-cause variation
e.g insertion sequences
infections of the oesophagus
BVDV mucosal disease
newcastle disease
viral - ulcers
What does LEE do ?
-encodes a type III secretion system
-translocate intimin receptor into the host cell that the bacteria attaches to
In what ways can a pathogen cause diarrhoea ?
-hypersecretion - trigger cl secretion on intestine e.g ETEC -e.coli
-villous atrophy e.g attaching and effacinf e.coli, rotavirus , parvovirus
-infiltrative and proliferative distortion of mucosa e.g lawsonia , M.AVIUM ( paratuberculosis )
-mucosal necrosis e.g brachyspira , clostridium .perfringens , e.coli and salmonella species
what does FORL stand for ?
Feline odontoclastic resorptive lesions
