Microbiology 1 Flashcards
What are t/he 5 different major groups of human pathogens?
Protozoa - eukaryotes Fungi - eukaryotes Bacteria - prokaryotes Viruses - non living Prion proteins
What are the difference between a eukaryote and a prokaryote?
Eukaryotes - bigger
Eukaryotes - complex where as prokaryotes are simple
Eukaryotes - multi cellular (pro = single celled)
Eukaryotes - no/flexible cell wall
Prokaryotes - rigid walls
What structures do a prokaryote have that Eukaryotes dont?
Plasma membrane
Cell wall (peptidoglycan)
Ribosomes
Capsule/flagellar/pili
What is a nucleoid and where is it found?
Contains DNA and proteins
No nuclear membrane
Primitive DNA
Found in Prokaryotes
How many layers of peptidoglycan do gram negative bacterias have?
Single layer
Describe the gram negative cell wall?
Outer membrane
Layer of Peptidoglycan
Inner membrane
What are flagella and fimbriae for?
Adherence and sex
What do bacteria (prokaryotes) need for growth?
Food Moisture Correct temperature (37 degrees) Correct pH (around 7.4) (Oxygen)
What are the different types of atmospheres?
Aerobic - growth in presence of O2 (some of these organisms can gown anaerobically but less well)
Microaerophillic - atmosphere with reduced conc of O2 and enriched with CO2
Anaerobic - no O2 present
What are prion proteins?
Infections proteins that have no DNA or RNA
Describe prion proteins
They cannot be removed by disinfection or sterilsation
Describe Viruses?
They have either RNA or DNA (single or double stranded)
Have a protein coat +/- a lipid envelope
Describe bacteria?
Contain DNA and RNA
One double stranded chromosome (sometime plasmids too)
Cell membrane and cell wall +/- capsule
Flagella/Pili
What are plasmids?
Circular bits of DNA in the cytoplasm
What is a pathogen?
A harmful organism
What is a commensal?
An organism that is part of the normal flora
What is an opportunistic pathogen?
An organisms that will probably only cause infection in an immunocompromised individual
(an organism that causes infection when opportunity/change in natural immunity arises)
What is a contaminant?
An organism that has got into a culture by accident
What is pathogenicity?
The ability of a microorganism to produce disease
What is virulence?
The degree of pathogenicity of an organism (ie. how easily can the organism cause disease)
What can bacterias produce?
They can produce toxins (enzymes) which can kill us
What toxins do gram negative and positive bacteria produce?
Exotoxin - gram positive - produced inside the cell then exported from it
Endotoxin - gram negative - produced on the cell wall
What can some of the toxins do?
They can interact with cells of the immune system causing the release of cytokines
They can also damage red/white blood cells making vessels leaking, causing decreased BP, affecting blood clotting, causing sepsis and septic shock.
What can some gram positive bacilli do?
They can form spores
- C.Diff
- Bacillus (bacillus anthrax)
What is a spore?
Its inactive, hardy form of bacteria that cannot replicate but can survive adverse conditions fort many years.
What is anthrax linked to?
Heroin - drugs
spores form from animal skin survived in heroin powder
Describe fungi?
Moulds - produce spores e.g. aspergillum, does not stain
Yeasts - reproduce by budding, e.g. candida, stain as large gram positive oval structures.
What is sterilisation?
Destruction of 99.99% of micro-organisms and spores
- examples, steam under pressure, heat, irradiation etc
What is disinfection?
Removal/destruction of PATHOGENIC micro-organism, enough to make an item safe
-example, hot water, chemicals.
