week 1 - fungal cell membrane and cell wall

Question 1

membranes of fungi

Answer 1

• Typical eukaryotic membranes
• Ergosterol replaces cholesterol
  o Antifungi specific medicine only target fungi

Question 2

cell walls of fungi
outer layer

Answer 2

• Outer layer of glycoproteins (sugar molecules bound to proteins)
  o Cell wall proteins (CWP)
  o Mannans (mannose polymers)
   Covalently linked to CWP

Question 3

cell walls of fungi
inner layer

Answer 3

• Inner layer of skeletal polysaccharides
  o Chitin
   Polymer of N-acetylhlucosamine (b-1.4-)
• Same sugar molecule as peptidoglycan
   Forms microfibrils
  o B-1,3-glucan
  o B-1.6-glucan links CWP to skeletal polysaccharides

Question 4

candid albicans

Answer 4

2 part cell wall

Tend to be linked to amino acids with a spare oxygen or amide group

Question 5

not all fungal walls are the same

Answer 5

• Most have chitin and glucans
• Cryptococcus have
  o Melanin –> causes irritant
  o Capsule –> similar to bacteria capsule

Question 6

antifungal agents

Answer 6

• Target cytoplasmic membrane
  Cell wall structures are not generally found in other organisms
• So useful for targeting

Question 7

antifungal agents
polyenes

Answer 7

• Amphotericin B
  Target
• Binds ergosterol in fungal membranes
• Disrupts membrane function
  Selectivity
• Eukaryotes have cholesterol in their membranes
• Still very toxic to humans

Question 8

antifungal agents
- target fungal cell wall

Answer 8

Echinocandins
- Used for systemic fungal infections in immunocompromised patients
- Inhibit the synthesis of glucan in the cell wall
- Inhibit 1,3-beta-glucan synthase