Anabolic Metabolism: Complex Lipids

Question 1

Diagram the synthesis and interconversion of phospholipids

Answer 1

Precursors: Phosphatidic Acid and 1,2-DAG

1,2-DAG - turns in to Phosphatidyl ethanolamine and Phosphatidyl choline through the addition of CDP-ethanolamine/CDP-choline

Cardiolipin - 2 1,2-DAG on glycerol molecule

Phosphatidyl Serine - 1,2-DAG + serine

Inositol - 1,2-DAG + inositol

*Energy for synthesis comes from CTP

Question 2

Identify the sites of phospholipid hydrolysis by phospholipases

Answer 2

A1 - fatty acid chain furthes from phosphate
A2 - middle Fatty acid chain
Phospholipase C - cleaves on side of Phosphate closest to fatty Acid
Phospholipase D - cleaves further away from Fatty acid

Question 3

Follow the synthesis of ceramid, the central precursor of sphingolipids

Answer 3

Sphingolipids = fatty acids and serine, one FA has to be palmitate

Palmitate->Palmitoyl CoA + fatty acid = Ceramide

Question 4

What is the important of Vitamin B12 and Vitamin B9

Answer 4

They are needed to remethylate SAM so SAM can methylate P-ethanolamine to P-choline

High levels of Homocystein is associated with Vitamin B12, B9 deficiency

Question 5

Describe the symptoms exhibited in the major sphingolipid recycling disease states

Answer 5

Tay-Sachs - buildup of GM2
Gaucher's - ceramide buildup
Sandhoff's - globoside buildup
Fabry's - build up of something
Niemann-Pick - sphingomyelin buildup