Unit 3 - Mobilisation of Energy Flashcards
(48 cards)
describe the process of mobilisation of lipids induced by hormones
adrenaline/ glucagon bind to a GPCR
- this activates adenylate cyclase - cAMP -PKA activates lipases that break down TAG into DAG into MAG which then become fatty acid and glycerol
how are fatty acids and glycerol used?
fatty acid - activated/ oxidised
glycerol - glycolysis
what are fatty acids attached to in the blood?
albumin
which enzyme is needed for fatty acid activation?
acyl coA synthetase = thiokinase
how does fatty acid activation happen
ATP + fatty acid forms acyl-adenylate intermediate which then binds with coA and forms acyl coA + AMP
where are short/medium chain fatty acids activated?
within mitochondrion
where are long chain fatty acids activated?
in cytoplasm
how is acyl coA from long chain fatty acids transported into the mitochondrion?
via carnitine shuttle
- acyl coA transferred onto carnitine via CPT1
- translocase transfers acyl carnitine into mitochondrion
- acyl coA regenerated by CPT2 - releasing free carnitine
what are the four steps of oxidation of beta carbon
oxidation, hydration, oxidation, hydrolysis
which enzyme cleaves the alpha and beta carbon of the fatty acid? what products are produced?
enzyme: thiolase
produces acetyl coA + acyl coA (with 2 fewer carbons)+ NADH + FADH2
how are the products of beta oxidation used?
acetyl coA - fed into TCA cycle
FADH/ NADH2 - directly into electron transport chain
what structure are lipids transported in?
lipoproteins - chylomicrons, VLDL, LDL & HDL
what do lipoproteins contain?
TAG, cholesterol, phospholipids, apolipoproteins
what do VLDL and chylomicrons transport?
lipoproteins rich in TAG to cells via lipoprotein lipase
what does VLDL become?
after stripping TAG becomes more dense so remodelled in liver into LDL which delivers cholesterol to the cells
what is cholesterol used for?
used in membranes or synthesis of steroid hormones
what is the role of HDL?
brings excess cholesterol from cells to liver (reverse cholesterol transport)
what is the term for liver excreting excess cholesterol as bile or bile salts?
hypercholesterolaemia
what process allows uptake of VLDL and LDL into liver?
receptor mediated endocytosis
how do chylomicrons remnant contribute to atheroscelerosis?
pass into epithelial lining and become oxidised - then taken up by macrophages which become foam cells and increase plaque in arteries
what two molecules are needed to begin the synthesis of cholesterol?
acetoacetyl CoA + Acetyl CoA
explain the synthesis of cholesterol
acetoacetyl CoA + Acetyl CoA = mevalonate (catalysed by HMG CoA reductase - requires NADPH)
mevalonate - squalene - cholesterol
how do statins inhibit the synthesis of cholesterol?
target mevalonate synthesis by inhibiting HMG CoA reductase
what enzyme catalyses the conversion of glucose 6P to glucose 1P?
phoshoglucomutase
