phospholipids and sphingolipids Flashcards
what do phospholipids contain
1,2-diacylglycerol and a nitrogenous base connected by a phosphodiester bond to C-3 of the glycerol backbone
what are fatty acids at C1
palmitate or stearate
what are fatty acids at C2
unsaturated
name the important constituents of cell membranes
-involved in conferring structural and functional integrity to membrane
-involved in generating intracellular signalling mediators
-involved in generating extracellular signaling mediators
-constituents of myelin
amount of dipalmitoyllecithin
80%
how is surfactant produced
by type 2 alveolar epithelial cells and prevents athelectosis by reducing the surface tension of the fluid layer in the avoeli in the lungs
describe respiratory distress syndrome in neonates before the 28th week and between the 28th week and 34th week
prior to the 28th week of gestation the fetal lung produces shingomyelin
from the 28th week type 2 alveolar cells increase and utilise their glycogen stores to produce dipalmitoyllecitihin
what happens during respiratory distress syndrome after the 34th week
the lung is functionally fully mature
what affects the degree of RDS
prematurity of the infant
how can RDS be predicted
by the screening of amniotic fluid for the ratio of lechitin : sphingomyelin
what does the ratio of 2 or greater for lechitin : sphingomyelin mean
maturity
what does a ratio of 1.5 mean
75% risk of developing RDS
what do phospholipids do
have important detergent properties in bile so increase the solubility of cholesterol
what forms sphingolipids backbone
long chain amino alcohol, sphingosine
what is the core molecule of all sphingolipids
ceramide
describe sphingomyelin
-major component of neuronal membranes
-the only sphingolipid that is a phospholipid
how is ceramide converted to sphingomyelin
by sphingomyelin synthase
what are glycosphingolipids
glucose and/or galactose units attached to C1 of the sphingosine moiety by B-glycosidic bond
how are cerebrosides synthesized
from ceramide and the activated nucleotide sugars
what are globosides
cerebrosides with more than one sugar unit
what are gangliosides
glycosphingolipids containing sialic acid
what is Tay-Sachs Disease
inherited GM2-gangliosides causing accumulation of GM2 in lysosomes, particularly in neural tissue
what does Tay-Sachs disease result in
progressive neurodegeneration with paralysis, dimentia and blindness
