FATTY ACID SYNTHESIS WORKSHEET 9

Hypercaloric state

A condition where there is an excess of calories consumed.

What happens to carbs and proteins eaten in excess?

They are converted into fatty acids and incorporated into triglycerides.

Organ for lipid conversion

The liver.

Mechanism of transport for lipids out of the liver?

They are packed into VLDL in the liver.

Destination for transported lipids from the liver?

Adipocytes.

Barrier protein for stored energy

Perilipins.

Circumstances for fatty acid oxidation

Occurs under low glucose conditions or increased activity.

Circumstances for fatty acid synthesis

Occurs under high glucose or caloric excess.

Main substrate for fatty acid oxidation

Fatty acids.

Main substrate for fatty acid synthesis

MalonylCoA.

Location of fatty acid oxidation

Mitochondria.

Location of fatty acid synthesis

Cytosol.

Mitochondrial transport mechanism for oxidation

Carnitine shuttle.

Rate limiting enzyme for oxidation

CAT I.

Mitochondrial transport mechanism for synthesis

Citrate shuttle.

Rate limiting enzyme for synthesis

AcetylCoA carboxylase (ACC).

Hormones controlling fatty acid/glucose metabolism

Main ones are glucagon, epinephrine and insulin.

Regulatory enzymes in fatty acid metabolism

CAT I, AcetylCoA Carboxylase (ACC), Hormone sensitive lipase (HSL).

What hormone is released in a high carbohydrate/energy rich environment?

Insulin

Effect of insulin in high carbohydrate environment

Activates ACC and inhibits HSL.

End result of ACC activation in a high carb environment?

Increases the conversion of AcetylCoA to MalonylCoA.

Effect of MalonylCoA on CAT I in a high carb environment?

Increased levels of MalonylCoA inhibit CAT I which prevents fatty acids from entering the mitochondria for oxidation.

Effect of HSL inhibition in a high carb environment?

Prevents stored lipids from being released from the adipocytes.

Hormones released in low carbohydrate environment

Glucagon and epinephrine.

Effect of glucagon on regulatory enzymes (ACC and HSL)?

Inactivates ACC but activates HSL.

End result of ACC inactivation in a low carb environment?

Malonyl-CoA falls, allowing fatty acids to enter the mitochondria and become the major fuel.

Effect of glucagon on HSL in a low carb environment?

Triggers HSL and the mobilization of fatty acids from the adipose tissue.