Microbiology Flashcards
Name 5 microorganisms/ infection agents in decreasing size
parasites, fungi, bacteria, viruses and prion proteins
what are prion proteins
infectious proteins that have no DNA or RNA
Why does surgical equipment have to be destroyed after being used on a patient with a prion disease?
because prion proteins cN NOT VE RELIbly removed by sterilisation or disinfection
what do eukaryotic cells contain
Nucleus, nucleolus, plasma membrane, mitochondria, ribosome, Golgi apparatus, endoplasmi reticulum
what are eukaryotic cells
fungi and protozoa
what are prokaryotic cells
bacteria
what do prokaryotic cells contain
ribosomes, DNA, cell envelope, cell membrane
what colour do gram neg cells stain
pink
what colour do gram positive cells stain
purple
why do gram positive cells stain purple
because they have a thick layer of peptidoglycan which retains purple stain
why do gram neg cells stain pink
only have a thing layer of peptidoglycan
why is it important to know the gram stain
many antibiotics act on bacteria cell wall, o it is important to know if the cell wall is arm positive or gram negative to know which antibiotic will work.
what organisms don’t stain well
mycobacterium tuberculosis (organism that causes tb) and treponema palladium (organism that causes syphilis)
what is needed for bacteria to grow
food, moisture, correct temp and correct pH
Bacterial Growth phases
lag phase, log phase, stationary phase and death phase
lag phase
bacteria only present in small numbers and DNA has to be replicated
log phase
bacteria can multiply exponentially
stationary phase
maintains constant levels
death phase
resources begin to run out and some bacteria die
3 main types of atmosphere bacteria grows in
aerobic, microaerophilic and anaerobic
aerobic growth
growth in presence of oxygen
microaerophilic
atmosphere with a reduced concentration of oxygen and enriched with CO2
anaerobic
no oxygen present in atmosphere
how often can bacteria replicate in ideal growth conditions?
every 20 minutes
why do some bacteria make us ill?
gram positive bacteria produce exotoxins, usually produced inside the cell and exported from it. Gram negative bacteria produces endotoxins which is part of the bacterial wall.
what type of cell produces spores
gram positive
how can you identify different bacteria
gram stain reaction, atmosphere they grow in, shape and other criteria such as biochemical tests
pathogen
harmful organism
commensal
organism that is part of the normal flora
opportunistic pathogen
an organism that will probably only cause infection in an immune-compromised individual
contaminant
an organism that has got into a culture by accident
pathogenicity
the ability of a microorganism to produce disease
virulence
the degree of pathogenicity of an organism
what kills fungi
anti fungal treatment , not antibiotics
sterilisation
destruction and removal of 99.9% of micro organisms and spores
disinfection
removal or destruction of pathogenic micro organisms enough to make an item safe
how to disinfect something
use hot water or chemicals
