1. Introduction To MicroB

Question 1

Creutzfeld-Jacob Disease due to ?

Answer 1

• Prions
• self-replicating proteins

Question 2

Creutzfeld-Jacob Disease affects ?

Answer 2

• affects brain
• neurodegenerative disorder
• fatal in short time, usually die in 8 months

Question 3

Gram +ve bacteria appear gram - ve after awhile if too much _____ is put.

Answer 3

Ethanol (why?)

Question 4

Gram stain: What step differentiates bacteria with a thick and thin peptidoglycan cell wall?

Answer 4

Decolourising using acetone and alcohol

Question 5

Gram -ve bacteria has more ______ than gram +ve bacteria

Answer 5

Lipopolysaccharides

Question 6

Difference between gram +ve and gram -ve bacteria?

Answer 6

Gram +ve: thicker peptidoglycan layer
Gram -ve: lipopolysaccharide (endotoxin) in cell wall

Question 7

Why is lipopolysaccharide in gram -ve bacteria harmful?

Answer 7

1. LPS binds to human cells via TLR4, CD14
2. LPS cause septic shock even when bacteria dead: increase vascular permeability & excessive blood vessel dilation=> end-organ failure, death

Question 8

Creutzfeld-Jacob disease in humans is due to the spread of ____________ from cows.

Answer 8

Bovine spongiform encephalopathy (mad cow disease)

Question 9

Surface components of bacteria:

Answer 9

1. Fimbriae and pili - allow adhesion to other bacteria or host surfaces
2. Flagella - allow bacteria to move
3. Capsules - protect bacteria from host immune response
4. Lipopolysaccharides (endotoxin) - within the second, outer membrane of gram -ve bacteria

Question 10

Properties of virus:

Answer 10

1. Obligate intracellular pathogens (cannot live outside host cell)
2. Do not contain enzymes that allow replication on its own
3. Replicate in host cell!