Sphingolipids

Question 1

Found in the outer leaflet of the cell membrane form part of the glycocalyx of the cell surface

Answer 1

Glycosphingolipids

Question 2

Functions of sphingolipids

Answer 2

In intercellular communication and contact
As receptors for bacterial toxins
As ABO blood group substances

Question 3

Are lysosomal storage diseases with defects in the catabolic pathway for sphingolipids

Answer 3

Sphingolipidoses

Question 4

Principal structural lipid of the membranes of nervous tissue

Backbone: sphingosine (amino acohol) not glycerol

4C

Answer 4

Sphingomyelin

Question 5

Fatty acids present in the sphingomyelin of myelin sheath

Answer 5

Lignoceric acid

Nervonic acid

Question 6

Fatty acid present in the sphingomyelin of gray matter

Answer 6

Stearic acid

Question 7

Sphingomyelin is converted to

Answer 7

Ceramide and choline

via sphingomyelinase

Question 8

Ceramide + Choline is converted to

Answer 8

Sphingosine and fatty acid

via ceramidase

Question 9

Due to deficiency of sphingomyelinase

Mental retardation
Ataxia
Seizure
Macular degeneration and cherry red spot

Answer 9

Niemann-Pick Sphingomyelinase Disease

Question 10

Due to deficiency of ceramidase

Answer 10

Farber’s Ceramidase disease

Question 11

Due to deficiency of beta glucosidase

Three forms

Answer 11

Gaucher’s Beta Glucosidase Disease

Question 12

Marked hepatosplenomegaly

Severe neurologic progression to death

Answer 12

Infantile 1-2 months

Question 13

Milder neurologic involvement

Answer 13

Juvenile 2-6 years

Question 14

Non-neuropathic form

Answer 14

Adult

Question 15

Also called globoid leukodystrophy

Due to deficiency of beta galactosidase

Galactosylceramide accumulates in the white matter

Infantile disease 2-6 months

Mental retardation
Leukodystrophy
Optic atrophy
Presence of globoid cells in the brain

Answer 15

Krabbe’s disease

Question 16

Sulfogalactocerebroside
Sulfuric acid ester of galactosylceramide

Major sulfolipid of the brain

Accounts for 15% of the lipids of the white matter

Answer 16

Sulfatide

Question 17

Due to deficiency of arylsulfatase A

Mental retardation
Leukodystrophy
Optic atrophy
Psychosis
Dementia

Answer 17

Metachromatic leukodystrophy

Question 18

Ceramide oligosaccharides

Sugars present are usually glucose, galactose or N-acetylgalactosamine

Answer 18

Globoside

Question 19

Example of globoside

Answer 19

Lactosylceramide component of erythrocyte membrane

Ceramide trihexosidase - abundant in the kidney

Question 20

Due to deficiency of alpha-galactosidase

Ceramide trihexoside accumulates in the kidney progessing to renal failure

Other/s: skin rash, pains in lower extremities

Answer 20

Fabry’s disease

Question 21

Contain sialic acid or N-acetylneuraminic acid

Highly concentrated in the ganglion cells of the CNS particularly in nerve endings

CNS is unique because more than half of sialic acid is in ceramide-lipid bound form

Answer 21

Gangliosides

Question 22

Due to deficiency of a beta-galactosidase

GM1 accumulates in the brain and other organs

Mental retardation
Seizures
Blindness
Impaired psychomotor function
Hepatosplenomegaly
Cherry red spot in 50% of infantile form

Answer 22

Generalized gangliosidosis

Question 23

Due to deficiency of hexosaminidase A
GM2 accumulates in the brain

Forms
infantile (3-6 months)
juvenile
adult

Mental retardation
Seizures
Blindness
Cherry red spot on macula

Answer 23

Tay Sach’s disease