Sphingolipids

Question 1

Structure of sphingolipids

Answer 1

• Sphingosine molecule as backbone (not glycerol)
• Fatty acid chain attached to sphingosine
• Long chain of carbon atoms
• Simple or complex sugar linked to alcohol on carbon 1

Question 2

What is the most common sphingolipid?

Answer 2

Sphingomyelin - only one of the sphingolipids that is a major component of biological membranes

Question 3

Which sphingolipid deviates from generic structure and how?

Answer 3

Sphingomyelin

Has a phosphorylcholine group instead of sugar

• Class of phospholipids called PC
• Head group incorporates choline

Question 4

What do all glycosphingolipids (Glycolipids) contain?

Answer 4

A sugar attached to carbon 1 of sphingosine

Question 5

Where are glycolipids exclusively found?

Answer 5

In outer leaflet of membrane

Question 6

In the membrane, the sugar groups of glycolipids are exposed at cell surface. What is purpose of this?

Answer 6

1. Interactions of cell with its surroundings (cell-cell adhesion)
2. Allows membrane to act as recognition sites for certain chemicals
3. Act as antigens and receptors for hormones and signalling molecules

Question 7

What are 2 main types of glycosphingolipids?

Answer 7

1. Neutral glycosphingolipids

2. Gangliosides

Question 8

What do neutral glycosphingolipids contain?

Answer 8

Only contain neutral sugar

Question 9

What do gangliosides contain?

Answer 9

Contain one or more sialic acid residues linked to sugar

Question 10

What are the gangliosides?

Answer 10

Ganglioside GM1, GM2 and GM3

• GM3 has 2 sugars attached to tail
• GM2 has 3 sugars attached to tail
• GM1 has 4 sugars attached to tail

Question 11

How to glycolipids tend to self-associate?

Answer 11

Via hydrogen bonds between their sugars and through their lipid tails
- Self-aggregation of GM1 lipids may be driven by the sugars in GM1 lipids