Lecture 9 - Fatty Acid Oxidation

When does fatty acid oxidation occur?

When glucose levels are low

What substance is responsible for emulsifying lipids?

Bile

Where is bile produced?

Liver

Where is bile stored?

Gallbladder

What enzyme is responsible for breaking ester bonds in the triglycerides during digestion?

Lipase

Where is lipase produced?

Exocrine portion of the pancreas

What happens to lipids after they enter the intestinal epithelial cells?

Packed into chylomicrons

How do lipids travel to their target cells?

Enter lacteals, then lymphatics, then blood

What determines where lipids go?

Apolipoproteins on the surface of the chylomicrons

What enzyme helps lipids to get ‘umpacked’ at the target cell?

Lipoprotein lipase

What happens to carbs and proteins eaten in excess?

converted to fatty acids and incorporated into triglycerides

Where are carbs and proteins converted to fatty acids to be incorporated into triglycerides?

Liver

How are excess carbs/proteins transported after being incorporated into tryglycerides?

packed into VLDL in the liver

Where are the carbs/proteins likely to end up after being converted to fatty acids and packaged into tryglycerides?

Adipocytes

What proteins can form a barrier that ensure our stored energy source is only used if necessary?

Perilipins

What is the main stimulus for lipids being liberated from storage/

low blood glucose

What hormone and neurotransmitters are responsible for triggering the liberation of lipids from storage?

Glucagon and epinephrine

What is activated when epinephrine binds to receptors on the adipocyte?

PKA

What is the main enzyme used to liberate lipids from storage?

Hormone sensitive lipase (HSL)

How is hormone sensitive lipase activated?

phosphorylated by PKA

What happens when perilipin is phosphorylated by PKA?

access is allowed for lipid droplets in thadipocytes

What is the site of lipid oxidation?

Mitochondrial matrix

How do fatty acids get to the mitochondrial matrix?

Carnitine shuttle

What is the rate-limiting enzyme used for lipid oxidation?

CATI

What substance is used in lipid oxidation?

Carnitine

What is produced after one round of beta-oxidation?

1 Acetyl CoA

1 FADH2

1 NADH+ H+

Where does Acetyl CoA go after being produced in beta-oxidation?

enters the Krebs Cycle

Where do FADH2 and NADH go after being produced in beta-oxidation?

oxidative phosphorylation

What is an intermediate in the oxidation of an odd-numbered fatty acid?

Propionyl CoA

What coenzymes are required for odd-numbered fatty acid oxidation?

Biotin and coenzyme B12

What is the final product of odd-numbered fatty-acid oxidation?

Succinyl CoA

Where does Succinyl CoA go after being produced in odd-numbered fatty acid?

Enters Krebs Cycle

used to produce Heme

What processes do excess carbs go through to enter fatty acid oxidation?

Glycolysis, then pyruvate oxidation to make Acetyl CoA

What is the goal of the carnitine shuttle?

get fatty acids in the mitochondria where the enzymes are

What enzyme is required to get the fatty acid into the outer membrane?

Fatty Acyl CoA Synthetase

What enzyme is required to get the fatty acyl carnitine into the mitochondrial matrix?

Carnitine Acyl Carnitine Translocase

What molecule convers the fatty acyl carnitine to fatty acyl CoA?

CAT II

What is the total yield for a 16 C molecule during beta oxidation?

129 ATP

What enzymes do MUFAs require?

isomerase

What enzymes do PUFAs require?

Reductase and isomerase

What protein gives the fatty acids a ride to the target cells?

Albumin