PW - Membrane Proteins

Question 1

What are the four major classes of lipids found in cell membranes?

Answer 1

1. Phospholipids
2. Cholesterol
3. Sphingolipids
4. Glycolipids

Question 2

What is involved in the structure of phospholipids? (4)

Answer 2

Glycerol backbone
Ester linkages
Acyl chains
Phosphate group

Question 3

What are 2 classes of phospolipds?

Answer 3

Neutral Phospholipids

• Ethanolamine
• Choline

Negative Phospholipids

• Glycerol
• Serine
• Inositol

Question 4

Describe 2 structures present in Sterols?

Answer 4

• 5-membered rings
• Hydroxyl group

Question 5

What are 2 features of Sphingolipids?

Answer 5

1. Major component of neuronal membrane
2. Primarily found in the plasma membrane

Question 6

What are 2 features of Glycolipids?

Answer 6

• Exclusively found on the outside of cell
• Synthesized in ER/Golgi

Question 7

How are gangliosides characterised?

Answer 7

Gangliosides – more complex – branched oligosacharides

Question 8

Why do lipids form bilayers? (3)

Answer 8

• Due to their amphipathic nature
• Acyl chains pack together forming hydrophobic interactions
• Water molecules appear on a hydrophilic surface

Question 9

What techniques are used to study the bilayer structure of cell membranes?

Answer 9

Combining diffraction patterns with X-rays helps determine the arrangement and organisation of lipids within the bilayer

Question 10

What are the roles of membrane proteins?

Answer 10

Transfer:

Material (nutrients etc.)

• Transporters (active)
• Channels (passive)

Information (cell signaling)

• Ligand Gated Channels
• Tyrosine Kinase Receptor
• G-Protein Coupled Receptors