s2m1 biochem – membrane lipids & cholesterol Flashcard

what do all membrane lipids contain?

which lipids do all body tissues synthesize? with which exception?

where are the enzymes for synthesis of these lipids?

they all contain fatty acids

phosphoglycerides & sphingolipids

except RBC don’t synthesize lipids

the enzymes are found in the cytosol ; on the membrane

what’s the typical composition of a phospholipid?
fatty acid tail + head group

what’s the precursor to phospholipids?

where does the energy come from for the synthesis?

precursor – DHAP (dihydroxy acetone phosphate)

energy – from cytidine triphosphate

(instead of adenosine triphosphate, ATP)

what can be used to make phosphatidylcholine?

what is needed to convert it?

phosphatidylserine

PL D enzyme ; SAM

what’s the only antigenic phospholipid?
cardiolipin

where is dipalmitoylphosphatidylcholine (DPPC) found?

what makes it & secretes it?

what disease is associated with it?

so how can we test for this disease?

how do we know if it’s not present?

it’s a component of lung surfactant

made by pneumocytes

respiratory distress syndrome – no surfactant in infant

test for it by measuring the DPPC to S(sphingomyelin) ratio

A ratio of 2 or above means maturity

 

where is phospholipase C used?

what is the function of the products?

in second messenger pathway

it cuts IP2 into:

DAG -> (protein kinase C)

IP3 -> (Ca2+ release)

1. what is phospholipase A2 used for?

2. what’s the function of the products?

3. what’s A2‘s second use?

4. what then fixes the problem?

5. what is A2;inhibited by?

6. where is alot of A2;found?

1. it releases arachadonic acid for thromboxane ; 2. prostaglandin synthesis

3. repair mechanism for distorted lipids in membranes (cuts out the bad ones)

4. Acyltransferase adds new FA

5. glucocorticoids inhibit it

6. pancreatic excretions are rich in ’em

what makes platelet activating factor water soluble?

what is it and what does it stimulate?

what effect does this have?

what effect does it have on neutrophils?

an acetyl group attached to it

it’s a hormone that binds to platelet receptors

it causes their aggregation resulting in thrombotic ; inflammatory events

causes neutrophils etc. to make superoxide radicals

where are phosphatidylethanolamine ; phosphatidylcholine found mostly?

what category do they fall under?

what disease are these associated with?

ethanolamine – nerve tissue

choline – heart muscle

they are both plasmalogens

associated with Alzheimer’s disease

what two compounds are the complex lipids synthesized from?
serine & palmitate

what are gangliosides ?

where are some of them found?

what else do they determine?

complex sphingolipids with large polar head groups 

6% in grey matter of brain

determine blood groups

what determines the different blood groups?

which enzyme determines A / B groups?

the sugar that’s attached to a ganglioside.

A – N-acetylgalactosamine transferase

B – Galactose transferase

Tay-Sachs disease

enzyme deficient?;

accumulating substance?

symptoms?

Hexoaminidase A

GM2;ganglioside

mental retard

blind

muscle weakness / seizures

Gaucher disease

enzyme deficiency?

accumulating substance?

symptoms?

Glucocerebrosidase

Glucocerebroside

hapatosplenomegaly

mental retardation

osteoperosis of long bones

;

Fabry disease

what’s unique about this disease?

enzyme deficiency?

accumulating substance?

symptoms?

the only x-linked disease

α-galactosidase

Globosides

kidney / heart failure

red-purple skin rashes

burning pain in lower extremeties

Krabbes disease

enzyme deficiency?

accumulating substance?

symptoms?

B-galactosidase

galacto-cerebroside

mental/motor deterioration

blind/deaf

loss of myelin in white matter of brain

how do you test for disorders of sphingolipid metabolism?

extract lisosomal enzymes (specific for what disease you’re testing for)

then add the compound they are supposed to break up.

if only half of it gets broken up, the person is a heterozygote for the disease etc.

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