Exam 3 Biochem-Lecture 30

Flashcard maker : Sarah Taylor
Which are a component of all membranes but are particularly abundant in the myelin sheath???


Sphingomyelins are……that are also …….

  •  sphingolipids
  • phospholipids.


What are important structural lipid components of nerve cell membranes???



The predominant sphingomyelins contain

palmitic or stearic acid N-acylated at carbon 2 of sphingosine.
The sphingolipids, like the phospholipids, are composed of

  • a polar head group
  • two nonpolar tails.

 The core of sphingolipids is
 the long-chain amino alcohol, sphingosine
Amino acylation, with a long chain fatty acid, at carbon 2 of sphingosine yields …..
a ceramide.


Sphingolipids include

  • the sphingomyelins 
  •  glycosphingolipids (the cerebrosides, sulfatides, globosides and gangliosides).

 Sphingomyelins are ……that are also ……




The sphingomyelins are synthesized by the transfer of phosphorylcholine  from phosphatidylcholine to a ceramide in a reaction catalyzed by what enzyme? 

 sphingomyelin synthase


Sphingomyelin is degraded by………. a lysosomal enzyme that hydrolytically removes phosphorylcholine, leaving a ceramide. 



Defects in the enzyme acid sphingomyelinase result in the lysosomal storage disease known as :

Niemann-Pick disease.


There are at least how many related disorder identified as Niemann-Pick disease???

4 related disorders


4 related disorders identified as Niemann-Pick

disease are

Type A

Type B

Type C

Type D


Type A and B of Niemann-Pick disease

result from

defects in acid sphingomyelinase


Type C1, C2 and D of Niemann-Pick disease

do not result from defects in acid sphingomyelinase
Glycosphingolipids, or glycolipids are composed of
 a ceramide backbone with a wide variety of carbohydrate groups (mono- or oligosaccharides) attached to carbon 1 of sphingosine.
The four principal classes of glycosphingolipids are

  • cerebrosides
  • sulfatides
  • globosides
  • gangliosides


Cerebrosides have

a single sugar group linked to ceramide
The most common of Cerebrosides is

  • galactose (galactocerebrosides)
  • with a minor level of glucose(glucocerebrosides).


Galactocerebrosides are found

are found predominantly in neuronal cell membranes
Gluco-cerebrosides are

  • not normally found in membranes, especially neuronal membranes
  • They represent intermediates in the synthesis or degradation of more complex glycosphingolipids.

Galactocerebrosides are synthesized from
ceramide and UDP-galactose
Glucocerebrosides are synthesized from
ceramine and UDP-glucose


Fabry disease is characterized by


  • accumulation of globosides
  • a reddish-purple skin rash
  • kidney and heart failure
  • burning pain in the lower extremities.


Gaucher’s disease is characterized


  • accumulation of glucocerebroside
  • liver and spleen enlargement
  • erosion of long bones and pelvis
  • mental retardation in infantile form only.



N-acetylneuraminic acid or sialic acid.


The linkage of NANA always involves ……..on the number ……… carbon of the carbohydrate.

the OH group



Gangliosides are very similar to globosides except that




they also contain NANA in varying amounts.


CNS is unique in that

more than 50% of the sialic acid is in gangliosides.

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