Week 4 sem 2 med1022

Question 1

Koch’s postulates

Answer 1

1. basically, able to get microbe from site of infection/lesion/where disease is occurring
2. get microbe pure n grow in culture
3. get microbe from culture to cause disease again in another human/animal
4. able to get same microbe from the 2nd infected human/animal again

Question 2

Molecular Koch’s postulates

Answer 2

1. particular strain of bacterium has particular gene/gene product causing disease
2. that gene is expressed in host
3. if u mutate the gene, u would lose virulence/ability to cause disease (or if u insert gene into avirulent strain, u can get ability to cause disease
4. ie if we have mutated the gene and eliminated virulence,
   then go the other way reintroduce the gene n restore virulence,( we call that
   complementation

Question 3

bacteria capsule

Answer 3

helps bac to stick to host cells/to each other

sticky slime layer made of polysaccharide

Question 4

to cause disease bac must

Answer 4

Enter body
overcome host barriers (e.g. physical barrier, immune response) 
adhesion to host
colonise host
multiply n spread
cause cell/tissue damage