Flashcards in lipids Deck (36)
what are some purposes of lipids?
stored form of energy
structural component of cell membranes
needed as enzyme cofactors
used in hormones
used for synthesis of vitamins A, D, E and K
used as signalling molecules
what is the structure of a fatty acid?
hydrocarbon chains with a carboxylic acid at one end.
what are the two forms which a fatty acid can be present in?
saturated or unsaturated
what are essential fatty acids?
acids that must be obtained via our diets
what are triacylglycerides(TAGs) formed from?
esters of fatty acids and glycerol
what are some function of TAGs?
major component of adipose tissue
at as insulation and dietary fuel
what is the structure of phospholipids?
glycerol bonded to two fatty acids and a phosphate group
phospholipids are amphipathic; true or false?
where does most digestion of triacylglycerols take place?
what mechanisms aid the digestion of TAGs in the small intestine?
emulsification by bile salts and peristalsis
what is most TAG digested to?
monoacylglycerol and two fatty acids
what are cholesterol esters broken down into?
cholesterol and a fatty acid
what are phospholipids broken down into?
hydrolysed to a fatty acid and lysophospholipid
what happens to the products of lipid digestion after they are digested?
they form mixed micelles with bile salts
what do mixed micelles do when they approach the brush border?
release their contents
what types of fatty acids would form mixed micelles?
long chain fatty acids
how are lipids transported in the body?
TAG, fatty acids and cholesterol esters are repackaged into chylomicrons, which are released into the blood via the lymphatic system.
what happens to chylomicrons when they reach tissues?
TAG is hydrolysed to fatty acids and glycerol by lipoprotein lipase.
what is the purpose of the free fatty acids produced from TAG hydrolysation?
used for energy
re-esterified into TAG for storage
how are free fatty acids transported?
lipoproteins, in a complex with serum albumin
how are fats transported?
high and low density lipoproteins?
what is the difference between high density and low density lipoproteins?
low density lipoproteins take cholesterol from the liver to other tissues
high density lipoproteins do the opposite, bring back cholesterol from the tissues to the liver for elimination
how many carbons are degraded at a time in beta oxidation?
what are the products of fatty acid metabolism via beta oxidation?
what are the 3 stages of beta oxidation?
what happens in the activation stage?
fatty acids are activated to form fatty acyl CoA in the cytoplasm
what happens in the transport stage?
carnitine shuttle transfers long chain fatty acyl CoA from the cytoplasm to the inside of the mitochondrion
what inhibits carnitine fatty acyl transferase and why is this significant?
malonyl CoA, which is used in fatty acid synthesis, therefore, synthesis and degradation cannot occur simultaneously
what happens in the degradation stage?
fatty acyl coA is dehydrogenated to form FADH2 and another intermediate.