Lecture 9: lipids

Question 1

Why are lipids important to living beings?

Answer 1

1. Essential component of biological membranes
2. Energy storage and fuel
3. Signal transduction
4. Antioxidants

Question 2

How can lipids be used in signal transduction?

Answer 2

1. Membrane lipids can be mobilized for signaling functions within the cytoplasm
2. They play the role of second messengers

Question 3

What are the classes of lipids?

Answer 3

1. Fatty acids
2. Phospho/glyceryl esters
3. Sphingolipids
4. Terpenoids
5. Sterols

Question 4

What enzymes are responsible for the biosynthesis of fatty acids?

Answer 4

Fatty acid synthetases

Question 5

Are naturally occurring fatty acids conjugated or non-conjugated?

Answer 5

Non-conjugated

Question 6

What are spingolipids derived from?

Answer 6

Sphingosine, a 18-C alcohol

Question 7

What is the structure of spingolipids?

Answer 7

A fatty acid bonded to the amino terminal of sphingosine
(also called ceramides?)

Question 8

What are the function of spingolipids?

Answer 8

1. They perform multiple signaling functions by acting as second messengers
2. Ceramide gets phosphorylated to form ceramide-1-phosphate which triggers downstream signaling

Question 9

Which sterol is a precursor for other steroids?

Answer 9

Cholesterol

Question 10

How do LDL and HDL cholesterol differ?

Answer 10

HDL has higher protein content than LDL

Question 11

What is the basic structure of Terpenoids?

Answer 11

Isoprene

Question 12

What are the ways lipids are targeted in therapeutics? Give examples.

Answer 12

1. Modulating lipid biosynthesis: statins to block synthesis of cholesterol
2. Modulating lipid oxidation: antioxidants to prevent free radicals from damaging lipids
3. Modulating lipid signaling: blocking steroid receptors to inhibit steroid action