Lipids and Membranes Flashcards

Sphingolipids differ from glycerophospholipids in that their backbone is:

Answer: Sphingosine

Sphingolipids are built on a sphingosine backbone (an amino alcohol) rather than glycerol, with a fatty acid attached via an amide bond to form ceramide.

Lipid rafts in cell membranes are enriched in which components?

Answer: Cholesterol and sphingolipids

Lipid rafts are dynamic microdomains enriched in cholesterol and sphingolipids that form a more ordered (liquid-ordered) phase and serve as platforms for signaling proteins.

The saponification number (saponification value) of a fat is a measure of:

Answer: The average molecular weight of fatty acids

The saponification value reflects the amount of alkali required to saponify a fat; higher values indicate shorter-chain fatty acids, since more moles (and thus more alkali) are needed per gram.

Which phospholipase cleaves the fatty acid at the sn-2 position of glycerophospholipids to release arachidonic acid?

Answer: Phospholipase A2

Phospholipase A2 cleaves the ester bond at the sn-2 position, releasing arachidonic acid (or other fatty acids) and a lysophospholipid.

Familial hypercholesterolemia is caused by a defect in:

Answer: LDL receptor function

Familial hypercholesterolemia is typically caused by loss-of-function mutations in the LDL receptor gene, impairing LDL uptake and causing elevated plasma LDL cholesterol.

Tay-Sachs disease results from accumulation of which lipid in neurons due to a missing enzyme?

Answer: GM2 ganglioside

Tay-Sachs is caused by deficiency of hexosaminidase A, leading to accumulation of GM2 ganglioside in neuronal lysosomes, causing progressive neurodegeneration.