Biochem Chapter 11 Fatty Acid and Triglyceride Catabolism

Fats are normally the major source of energy in liver and muscle and in most other tissues, with two major exceptions:

Brain and Red cells

The ______ of the fatty acid dictates where it is activated to CoA

length

What bypasses the impermeability of the mitochondrial membrane to coenzyme A

Carnitine Shuttle

The overall production of ATP per gram of palmitate is about _____ that per gram of glucose because glucose is already partially oxidized in comparison with palmitate.

twice

Caloric values of fat is twice of sugar

What is MCAD Deficiency

Medium Chain Fatty Acyl-CoA dehydrogenase deficiency

Inability to metabolize fat during fasting causing hypoglycemia

Treat by frequent feeding and avoid fasting

What is the principal sites of production of hydrogen peroxide (H2O2) in the cell, accounting for nearly 20% of oxygen consumption in hepatocytes.

Peroxisomes

What kind of fatty acids do peroxisomes oxidize

Very long and long branched

Not for short chain

What is Zellweger syndrome

Defect in import of enzymes into peroxisomes

Cause death

_______ is a class of hypolipidemic drugs that act by inducing peroxisomal proliferation in liver

Fibrates

What kind of fatty acids yield less FADH2

Unsaturated

Less FADH2 less ATP

_____-chain fatty acids produce succinyl-CoA from propionyl-CoA

Odd

The propionyl-CoA is converted to succinyl-CoA by which two vitamins

Biotin (B7) and Cobalamin (B12)

Phytanic acid requires _____ _____ to pristanic acid

What is Refsum’s disease

a oxidation

Refsum is neurologic disorder by accumulation of phytanic acid from genetic defect in a-oxidation

_______ is a pathway for regenerating CoA from excess acetyl-CoA

Ketogenesis

Excess acetyl-CoA not recycled to CoA shuts down liver metabolism and can’t do beta oxidation

What does the liver do with the excess acetyl-CoA that accumulates in fasting or starvation?

HMG-CoA synthase turn Acetyl-CoA to CoA so it can participate in B-oxidation

Can liver decompose Ketone Bodies

No it can only make them

They are then exported to blood

When do ketone bodies increase in plasma

Fasting and Starvation

What happens to ketone body in poorly controlled type 1 diabetes

High rates of lipolysis and ketogenesis leads to ketoacid and maybe life-threatening

What happens to ketone body in carnitine deficiency

Carnitine is needed to transport fatty acid to mitochondria for b-oxidation producing acetyl-CoA. When acetyl-CoA accumulates ketogenesis (acetyl-CoA converted to ketone bodies) happens.

Low carnitine causes hypoketotic hypoglycemia especially during fasting

Cushing’s syndrome, in which there are high blood concentration of ______, is characterized by hyperglycemia.

Cortisol (Cause gluconeogenesis and protein breakdown)

Also cause moon face and central obesity

Does TCA cycle slow down during fasting

Yes

Although it makes more energy, but during fasting oxaloacetate is low which slows down TCA cycle and the excess acetyl-CoA needs to be converted to ketone bodies to provide energy to tissues