Group 4

Question 1

symmetry of biological membranes

Answer 1

-biological membranes are asymmetrical
-2 leaflets have distinct lipid composition
- the outer leaflet contains glycolipids and glycoproteins
-lipids and proteins with carbs attached

Question 2

structure of biological membranes

Answer 2

all membranes share common properties
-approx 6nm thick
-stable, flexible and capable of self assembly
membranes also have unique features:
-different membranes contain different lipids and proteins, giving them distinct funtions

Question 3

Fluidity of biological membranes:
cholesterol

Answer 3

cholesterol modulates membrane fluidity
-cholesterol acts as a bidirectional regulator of membrane regulator of membrane fluidity:
-at high temps, it stabilizes the membrane, raises melting point

-at low temps, it intercalates between the phospholipids and prevents them clustering together and stiffening

Question 4

Plasma membrane

Answer 4

-trilaminar structure (oreo-like) that has a hydrated lipid bilayer
-lipid bilayers are made from phospholipids
-phospholipid bilayer has proteins embedded

Very dynamic:
-lipids can move easily within one leaflet
-movement between leaflets is slow and difficult

Question 5

Phospholipid structure

Answer 5

-phospholipids consist of a glycerol backbone bound by:
-2 non-polar fatty acyl molecules
-a polar head group linked by a phosphate residue
phospholipids are amphipathic
-hydrophilic heads
-hydrophobic tails

Question 6

Fluid Mosaic model

Answer 6

Fluid = components are mobile

Mosaic = diverse particles like proteins, carbs and cholesterol penetrate the lipid layer; components can interact

its a bilayer of amphipathic lipids
-has integral, peripheral and lipid-anchored proteins

Question 7

Biological membranes:
- The ______ structure is a lipid bilayer
- the lipid bilayer is made up of ____________
-_____________ are embedded in or associated with the phospholipid bilayer

Answer 7

• trilaminar
  -phospholipids
  -proteins

Question 8

The Outer Mitochondrial Membrane contains…

Answer 8

Enzymes and Porins

Question 9

The inner mitochondrial membrane contains…

Answer 9

A high protein to lipid ratio (3:1), double layered folds called cristae and it is rich in cardiolipin phospholipids