Lecture 21 - Lipid Metabolism: Fatty Acid Catabolism

Question 1

Why are fats good stores of energy?

Answer 1

Highly concentrated stores of energy
Inert
Oxidation of fatty acids wields lot of energy
Long chain fatty acids produce 2x more energy from same weight carb

Question 2

Transport in the Body

Answer 2

Insoluble in water

• dietary lipids emulsified and absorbed with bile acids in the small intestine as micelles
• carried around in lipoproteins

Question 3

Digestion of Lipids

Answer 3

Stomach 
- lingual and gastric lipases degrade triacylglycerol to 1,2-diacylglycerol + fatty acid
Small intestine
- degraded by pancreatic enzymes
Emulsification 
- bile salts
Absorption

Question 4

Mobilisation and Transport of Stored Lipids

Answer 4

Mobilisation
- stored triacylglycerols brought out of storage under influence of hormones
- activation of hormone sensitive lipase convert triacylglycerol to glycerol and 3 fatty acids
Transport
- fatty acids diffuse into blood and then transported to tissues
- fatty acids diffuse into cells
- then oxidised for energy production or repackaged by liver for export

Question 5

β-Oxidation

Answer 5

Used to generate ATP from Acyl CoA
Occurs in mitochondrial matrix
- inner mitochondrial membrane impermeable to fatty acids
Three steps:
1. Fatty acid activation by binding to CoA via Acyl CoA synthetase
2. Fatty acid transportation into mitochondrial matrix by adding to carnitine
3. Spiral repeated β-oxidation of fatty acids through four reactions to produce Acetyl CoA, FADH2 and NADH

Question 6

Cystic Fibrosis

Answer 6

Mutation in gene coding for cystic fibrosis transmembrane conductance regulator protein (CFTR)
Deficiency in CFTR leads to altered pH
Suffers from exocrine pancreatic insufficiency
Maldigestion and malabsorption