lipids Flashcards
what are the three classes of lipids
- fatty acid derivatives: fatty acids, triacylglycerols, phospholipids, eicosanoids
- hydroxy-methyl-glutaric acid derivatives: ketone bodies, cholesterol
- vitamins: A,D,E,K
How are triacylglyercides taken into tissue
- hydrolysis of TAG in small intestine by pancreatic lipase into fatty acids and glycerol.
- converted back to TAG in small intestine and packaged into lipoprotein called chlyomicrons.
- released into circulation via lymphatics and carried to adipose tissue to be stored as TAG. released as fatty acids when needed.
explain fatty acid catabolism
FA is activated by linking to coenzyme A outside the mitochondrion by the action of fatty acyl CoA synthase.
transported across the inner mitochondrial membrane using a carnitine shuttle.
FA cycles through sequence of oxidative reactions with C2 removed in each cycle.
what inhibits the carnitine shuttle
Malonyl-CoA
where can b-oxidation (fatty acid metabolism) not occur
brain
RBC
glycerol metabolisation equation
glycerol becomes glycerol phosphate via glycerol kinase. this uses ATP
glycerol phosphate can be either used for triacylglycerol synthesis or become dihydroxyacetone phosphate (DHAP) and enter glycolysis
what are the ketone bodies produced in the body and where are they produced
acetoacetate
acetone
b-hydroxybutyrate
*produced by liver mitochondria
control of ketone body production in the liver
when glucose is low fatty acids are broken down so NADH is high which is a high energy signal so will inhibit the TCA cycle so acetyl CoA goes into pathway making ketone bodies instead.
ketone body regulation by insulin/glucagon ratio
when insulin/glucagon ratio is high(fed state). lyase is inhibited and HMG-CoA is activated synthesising cholesterol.
when its low ketone bodies are synthesised instead.
