Lecture 5

Question 1

Plasma Membrane Components

Answer 1

Thin barrier, 8nm thick
Made up of:
Lipids (phospholipids [bilayer] and cholesterol [fluidity])
Proteins (embedded in bilayer, regulates traffic across membrane[integral and peripheral])
Carbohydrates (on extracellular surface of membrane, important in cell-cell recognition)
Also glycoproteins and glycolipids

Question 2

Cell Membrane Fluidity

Answer 2

Phospholipids of the membrane drift laterally and are held together by weak hydrophobic interactions

Question 3

Cholesterol in the membrane

Answer 3

Reduces fluidity at moderate temps but hinders solidification at lower temps
Overall: stabilizes fluidity

Question 4

HIV (example)

Answer 4

HIV can mimic and bind to the CCR5 receptor and CD4 co-receptor on the membrane, infecting it
Cannot infect cells lacking CCR5