Invasion + Attachment Flashcards
Disease
a pathological condition resulting from various causes (infection, genetic defect) and characterised by an identifiable group of symptoms
Pathogenicity
the ability to cause disease
Virulence
the ability of an agent of infection to produce disease
Infection
invasion of a host’s bodily tissues by disease-causing organisms, their multiplication and the host’s reaction to the organisms and the toxin they produce
Primary pathogen
micro-organisms that cause disease in healthy individuals
Opportunistic pathogen
microorganisms that are normally in contact with the host but cause disease when the host’s resistance is low
Effects of virulence
~ produces a metabolic burden on the cell
~ non-virulent mutants grow faster
Infective dose (ID)
no. of bacterial cells required to establish an infection
e.g. cholera >1,000,000 cells
dysentery ~10 cells
The lower the infective dose…
the higher the probability of infection
e.g. higer virulence
Zoonotic disease (zoonoses)
a disease that normally exists in animals but that can infect humans
Laminar flow
a fluid flows in parallel layers, with no disruption between the layers
Turbulent flow
the fluid undergoes irregular fluctuations, or mixing
What do the Alg genes code for?
alginate
~ an extracellular polysaccharide
What effect does low flow have on the growth of biofilms?
slow, compact growth
low nutrients
What effect does high flow have on the growth of biofilms?
rapid growth = unstable
prone to sloughing
high nutrients
Sloughing
the act of shedding or casting off dead tissue, such as cells
Autoinducers
small diffusible chemical messengers
Name the different types of N-Acyl-Homoserine Lactones.
OHHL (C6) - range BHL (C4) OdDHL (C12) - specific ~ each have same end group = active site ~ Pseudomonas aeruginosa
Quorum sensing
a coordinated response in ALL cells of the population
What’s the difference between a coordinated and an uncoordinated response?
in a coordinated response, gene product is only produced once quorum/threshold has been reached
Where are LuxI/LuxR homologues found?
Most of the main human pathogens
What does the LuxIR region do?
LuxR - produces activator proteins
LuxI - produces AHL precursor
How many bp are there between the LuxR and LuxI genes?
218bp
