Biochem-Triacylglycerols-Final exam

What are acylglycerols?

One or more fatty acids esterified to glycerol, forming mono-, di- and triacylglycerols

What are simple acylglycerols?

Contains same fatty acid composition

What are mixed acylglycerols?

Contains different fatty acid composition

Where are acylglycerols primarily found?

In fat deposits as a major lipid store and source of energy

What is the precursor molecule for phosphoacylglycerols?

Phosphatidic acid (1,2-diacylglycerol-3-phosphate)

What are the types of phosphoacylglycerols?

Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine

What are lysophospholipids?

Phosphoacylglycerols missing a fatty acid at the second position

What is ceramide?

A major precursor to sphingolipids that are formed by the esterification of sphingosine

What are the two major categories of sphingolipids?

Sphingophospholipids (sphingomyelin) and glycosphingolipids (cerebrosides, gangliosides)

What are cerebrosides?

Glycosphingolipids with a single sugar attached

What are gangliosides?

Glycosphingolipids with complex sugars attached and play a role in signal transduction

What is the first step in triacylglycerol synthesis?

DHAP is reduced to glycerol-3-phosphate by glycerol-3-phosphate dehydrogenase (in adipose tissue)

ATP gives phosphate to glycerol by glycerol kinase to form glycerol-3-phosphate (in liver/small intestine)

What is the final step in triacylglycerol synthesis?

1,2-diacylglycerol reacts with acyl-CoA to form triacylglycerol

What happens in the first step of phosphatidylcholine synthesis?

ATP donates a phosphate to choline, forming phosphocholine and ADP

What is the final product of phosphatidylcholine synthesis?

Phosphatidylcholine, formed from CDP-choline and 1,2-diacylglycerol

What is the significance of ceramide?

It plays roles in cell death programming, cell cycle regulation, and is a precursor for sphingomyelin and glycosphingolipids

What is the first step in ceramide synthesis?

Palmitoyl-CoA and serine combine to form dihydrosphingosine

What is the final step of ceramide synthesis?

Dihydroceramide is broken into ceramide and 2 hydrogen ions

What is sphingomyelin?

A sphingophospholipid formed from ceramide and phosphatidylcholine

Where is sphingomyelin synthesized?

The golgi apparatus

What is sphingomyelin’s function?

It forms the myelin sheath in nerves and brain tissue

What is the major glycosphingolipid in muscle cell membranes?

Glucosylceramide, composed of ceramide and UDP glucose

What is the major glycosphingolipid of myelin and nerve cell membranes?

Galactosylceramide, composed of ceramide and UDP galactose

What are gangliosides?

Components of ganglion cell membrane which is used in signal transduction

What are sphingolipidoses?

Decreased catabolism of sphingolipids due to a lysosomal enzyme defect

What enzyme deficiency causes Tay-Sachs disease, and what accumulates?

Hexosaminidase A deficiency which leads to accumulation of GM2 (ganglioside)

What enzyme deficiency causes Gaucher disease?

Beta-glucosidase deficiency which leads to glucosylceramide accumulation

What enzyme deficiency causes Niemann-Pick disease?

Sphingomyelinase deficiency which causes sphingomyelin accumulation

What is the role of lung surfactant?

It prevents alveoli from collapsing during exhalation and allows breathing

What deficiency causes respiratory distress syndrome in pre-term infants?

Dipalmitoylphosphatidylcholine deficiency

What happens in multiple sclerosis?

A loss of phospholipids and sphingolipids from white brain matter leads to demyelination