LM4 Flashcards
Bacterial exotoxins have the following properties
They are DS DNA icosahedral viruses with a diameter of about 80nm
In addition they have 20 triangular faces and have no envelope
Haemolysins produced by streptococci and staphylococci are
Membrane disrupting cytotoxins which form pores in red blood cells allowing the blood to be released
Can be detected by growing on blood agar plates and shows Beta haemolytic activity
Bacterial exotoxins have the following properties
Small, soluble heat labile proteins
sensitive to heating at 60-80 degrees C
The lipid A endotoxin molecule is located in
The lipopolysaccharide (LPS) molecule and is embedded in the outer leaflet of the outer membrane in Gram negative bacteria
Lipid A is at the proximal end of the LPS molecule in the outer membrane
The influenza virus can mutate easily because
It can undergo antigenic shift when the RNA segments of two different strains undergo reassortment in the host
For example a bird flu virus and a human flu virus together in the human host can produce an entirely new virus.
Biotrophic fungal diseases of plants
After penetrating the plant cell wall, the infection peg differentiates into a branched tubular structure called the haustoria which DOES NOT penetrate the plant cell membrane (evading a plant cell response) but allows sugars to be absorbed and phosphate to diffuse into the plant cell.
