Lipids 1: 10/04

Question 0

What are volatile fatty acids?
Structure?
Types?
Function?

Answer 0

• short chain fatty acids formed in the fermentation Compartements of herbivores
• acetate (2C), propionate (3C) and butyrate (4C) are the most common
• function is to act as metabolic fuels of precursors of fat.
• proprionate is a very important source of glucose for ruminants

Question 1

You should be able to describe the structure and function of the major lipid groups

Answer 1

1. Fatty acids (non esterfied, free) NEFA
   a) volatile FA (VFA): end products of digestion in herbivores
   b) long chain FA: metabolic fuel (metabolically active form of fat), transported on albumin in blood, building blocks for other lipids.
   
   • saturated
   • unsaturated (mono, poly)
     c) eicosanoids: cellular modulators➡ synthesised from unsaturated long chain fatty acids
2. Glycerol lipids:
   - a) riacylglycerols: fatty acid storage in adipose tissue, also transport form if fat in blood (lipoproteins)
   b) phospholipids: membrane structure, detergents in gut and cellular modulators
3. Sphingolipids: phospholipid like, membrane structure, detergent in gut, cellular modulators
4. Sterols (cholesterol): membrane and lipoprotein structure, hormone precursor, bile acid precursor, vitamin D precursor.

Question 2

What are the long chain fatty acids?

Answer 2

• more than 14 carbons
• defined according to chain length and degree if unsaturation
• 2 most common are: palmitic (C16:O) and stearic acid (C18:O). These comprise approximately 50% of fatty acids of adipose tissue triglycerides and 30% of fatty acids if membrane phospholipids.
• unsaturated fats have lower melting points as the number of C=C bonds increase because these bond are in cis position.

Question 3

Name the 2 most common saturated fatty acids?

Answer 3

Palmitic acid and stearic acid

Question 4

The site of the unsaturation is defined using one or more nomenclatures
Describe them

Answer 4

System 1: refer to page 41 of lecture notes