microbiology

Question 1

Define competitive exclusion

Answer 1

where co-occurring bacteria with the same niche compete for limited resources

Question 2

Describe how PCR works ? - including three main processes

Answer 2

melting
annealing
synthesis

1. reaction mix heated 95C , hydrogen bonds of DNA nucleotides broken down . Double stranded DNA will be denatured
2. 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

Question 3

How is PCR used in diagnosis ?

Answer 3

-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

Question 4

list and breifly describe the main mutations

Answer 4

-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)

Question 5

what does negative control do ?

Answer 5

minimise effect of external variables

Question 5

Define Genome

Answer 5

an organisms entire DNA - genes ( coding regions ) and non coding regions

Question 6

what does positive control do ?

Answer 6

allows you to make sure all your equipment is working properly . Making sure that the experiment can have a positive outcome.

Question 7

What factors can alter gut microflora ?

Answer 7

meds
stress
diet
genetics
co-concurrent infection

Question 8

Outline key features of enteric viruses

Answer 8

-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 )

Question 9

How do viruses enter cells ?

Answer 9

bind to sialic acid — integrins — other proteins on cell surface

Question 10

Define mitochondrial genome

Answer 10

single circular chromosome that encodes some proteins necessary for mitochondrial function

Question 11

Define microbiome

Answer 11

is the combined genetic material of the microorganisms in a particular environment

Question 12

What is the role of microbiome ? where does it differ

Answer 12

-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

Question 13

define role of microbiome in gut health and disease

Answer 13

-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

Question 14

How can you analyse genomes and microbiomes ?

Answer 14

PCR ,sequencing , Multi locus sequence typing MLST

Question 15

How does sequencing work ?

Answer 15

-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

Question 16

How is sequencing different from MLST?

Answer 16

-MLST uses whole genome

Question 17

Outline transcription and translation

Answer 17

transcription - DNA - RNA
translation - RNA - protein

Question 18

struc and func of bacterial chromosomes and plasmids

Answer 18

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

Question 19

How do bacteria transfer genes between each other ?

Answer 19

-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

Question 20

describe lytic transduction

Answer 20

-attach
-infect /inject
-lag phase - replication
-lyse - during lysis DNA can be packaged by mistake

Question 21

explain temperate phage transduction

Answer 21

• 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

Question 22

What are restriction endonucleases ?

Answer 22

they restrict the bacteria cell from constantly taking up DNA by degrading DNA not made in there own cell

Question 23

What is the struc and func of transposon ?

Answer 23

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

Question 24

infections of the oesophagus

Answer 24

BVDV mucosal disease
newcastle disease
viral - ulcers

Question 25

What does LEE do ?

Answer 25

-encodes a type III secretion system
-translocate intimin receptor into the host cell that the bacteria attaches to

Question 26

In what ways can a pathogen cause diarrhoea ?

Answer 26

-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

Question 27

what does FORL stand for ?

Answer 27

Feline odontoclastic resorptive lesions