0218 Lipid metabolism Flashcards
Two classes of lipid – acyl and sterol Complex acyl-lipids start with glycerol Lipids require specialised transport processes (lipoprotein or albumin) Exogenous pathways delivers dietary lipids Endogenous pathway distributes synthesised lipids Fatty acid mobilised by lipase at adipose tissue Fatty acids activated using CoASH Transport into mitochondria via carnitine shuttle system β-oxidation “strips” 2-carbons per round β-oxidation generates considerable amounts of
What are the 2 categories of lipids
Fatty acids and Sterols
What are some roles/fates of lipids
Steroid hormones (bio-signalling), Phospholipids (bio-membrane structure), Triglycerides and bile salts/acids (energy)
What are fatty acids made of
A non-polar hydrocarbon chain (tail) and a polar carboxylic acid group (head)
Describe the structure of complex lipids
Complex lipids are fatty acids attached to the OH group of glycerol (3 carbon compound). 2 fatty acids attached = diglyceride and 3 = triglyceride
Describe the structure of a phosphlipid membrane
it is a bilayer of phospholipids with the hydrophobic tails in the middle and the hydrophyllic heads on the outside.
True or false, all lipids have poor solubility
True
Define ampiphicity and it’s implications for lipids in aqueous environments
Ampiphicity is the property of having hydrophobic and hydrophyllic elements. Lipids therefore form structures such as liposomes, bilayers and micelles in aqueous environments
What is a lipoprotein and what is it’s role in lipid metabolism
A liproprotein is a spherical structure consisting of a phospholipid membrane containing apoplipoproteins and cholesterol. Inside these lipoproteins are triglycerides and cholesterol esters. THey are the primary transport mechanism for lipids across the body
Name some hormonal stimuli of fatty acid mobilisation
Adrenalin and glucagon
What is the name of the enzymes that hydrolyse fatty acids from triglycerides
Hormone sensitive lipases
What is the process through which fatty acids enter the mitochondria
Fatty acids enter the mitochondria through the carnitine shuttle system. Acyl-CoA is turned into Acyl-carnitine (CAT1) which is transported through the mitochrondrial membrane by a carnitine transporter (1 acyl-carnitine in, 1 carnitine out). Then Acyl carnitine is turned back into acyl-CoA (CAT2).
How is acyl-CoA turned into energy in the mitochondria
Beta oxidation. Acyl-CoA has 2 carbons cleaved off it’s structure per ‘round’. Each round produces one acetyl-CoA. Also produces FADH2 and NADH
How is fat catabolism regulated at the supply and intra-cellular level
Supply: mobilisation dependant on hormone sensitive lipase. Intrcellular: Malonyl-CoA (inhibits CAT-1)
Generally how long are the fatty acid chains in humans
14,16 or 18 Carbons long
What are apolipoproteins
In lipid transport, apolipoproteins function as structural components of lipoprotein particles, cofactors for enzymes and ligands for cell-surface receptors
