Fatty acid oxidation

Question 1

What are triglycerides broken down to?

Answer 1

Triglycerides are broken down to fatty acids and glycerol by lipases

Question 2

Phospholipases

Answer 2

• A1 – digestive system
• A2 – pancreatic juice, venoms.
• C – liberates diacylgylcerol.
• D – converts phospholipids to phosphatides

Question 3

Describe Fatty Acid β-oxidation

Answer 3

• Degradation pathway that removes C2 units.
• C2 units transferred to coenzyme A to make acetyl CoA.

–Citric acid cycle.

• Remainder enters oxidative pathway.
• Additional requirements for odd-numbered and unsaturated fatty acids.

Question 4

Where does Fatty Acid β-oxidation occur?

Answer 4

• Occurs in the mitochondria of eukaryotes.
• Fatty acids are activated by combination with coenzyme A.

–Fatty acyl CoA synthetases.

Question 5

Reaction with Carnitine

Answer 5

•Catalysed by carnitine acyltransferases.

Question 6

Long chain FAs transported across the mitochondrial membrane by

Answer 6

reversible reaction with carnitine

Question 7

FAs are a vital source of

Answer 7

of ATP for energy generation.

Question 8

What can also be used in amino acid synthesis?

Answer 8

Carbons

Question 9

Draw Fatty Acid β-oxidation

Answer 9

Question 10

Oxidation (1) and Hydration (2)

Answer 10

Question 11

Oxidation (3) and Thiolysis (4)

Answer 11

Question 12

Summary of Fatty Acid β-oxidation

Answer 12

Question 13

Fatty Acid Oxidation and ATP

Answer 13

• Vital source of ATP for energy generation.
• Carbons can also be used in amino acid synthesis

Question 14

Fatty Acid β-oxidation vs Synthesis

Answer 14

Question 15

Fatty Acid β-oxidation vs Synthesis

Answer 15

Question 16

Describe the regulation of fatty acid oxidation

Answer 16

• Controlled by substrate availability.
• Hormones regulate the [fatty acids] in blood.

–Insulin decreases this.

–Glucagon and adrenaline increases this.

•Fatty acid oxidation inhibited by insulin, promoted by glucagon and adrenaline.

Question 17

Describe the regulation by FA-CoA

Answer 17

• When there is plenty of glucose available, fatty acid CoA is converted to triacylglycerol in the liver.
• This is not oxidised as formation of malonyl CoA occurs when there is plenty of glucose.
• Malonyl CoA inhibits carnitine acyl transferase I.

–Results in triglyceride synthesis

Question 18

Describe the regulation of AMPK

Answer 18

• When ATP drops AMP rises (energy shortage).
• Activation of AMPK switches off synthesis and increases oxidation.

Question 19

What are Ketone Bodies?

Answer 19

•Alternative use of acetyl CoA (rather than citric acid cycle).

–Occurs when there is an imbalance of fat and carbohydrate degradation.

•Synthesized in liver of mammals.

–Major source of energy in peripheral tissues.

–“water-soluble lipids”.

•Produced in large amounts during starvation.

–Fuel for brain cells.

Question 20

The presence of ketone bodies

Answer 20

• Large amounts in untreated Type 1 diabetics.
• Smell of acetone on breath.
• Acetonic acid can cause blood pH to drop – diabetic ketoacidosis.