Lecture 6 Flashcards
What is lipogenesis
formation of lipids from CHO and proteins
Where does lipogenesis occur?
cytoplasm
What type of reactions occur in lipogenesis?
reductions (ie addition of H+ and use of NADPH
What are the two proteins important in lipogenesis
ACP (acyl carrier protein) and CE (Condensing protein)
What is the cofactor for CE protein?
cysteine
What are the 3 important steps in lipogenesis?
Acetyl CoA to Malonyl ACP to palmitate 16:0
What is the first fatty acid produced from glucose? Precursor to all other FAs
Palmitate
What is lipolysis?
breakdown of triclycerides by lipases into glycerol and free fatty acids for energy
what hormones activate and suppress lipolysis
epinpehrine and glucagon activate, insulin inhibits it.
What are the enzymes involved in lipolysis?
Triacylglycerol lipase
diacylglycerol lipase
monoacylglycerol lipase
Besides stimulating lipolysis, what other effect does insulin have on adipose cells/
inhibits the breakdown of fatty acid stores and increases stores.
What is beta-oxidation?
The oxidation of fatty acids in the mitochondria to Acetyl CoA
What is the carrier molecule for free fatty acids in beta oxidation
carnitine
what are the stages of beta-oxidation?
fatty acid activation (allows fatty acids in cytosol to enter mitochondria for oxidation). Oxidation of fatty acids (removes 2 carbon segments, one at a time, from a fatty acid.
What is the product of beta-oxidation?
Acetyl-CoA. This is shuttled into the krebs cycle and converted into energy (ATP)
What is cholesterol the precursor to?
Steroids in the body (eg glucocorticoids (cotisol), mineralocorticoids (aldosterone),
Bile salts - emulsification/digestion
steroid sex hormones - androgens, oestrogens, progesterones. Vitamin D synthesis, structural integrity of cell membranes.
How is cholesterol transported through the circulation/
lipoproteins
what is the storage form of cholesterol (in cells)
cholesterol esters
Where in the body does biosynthesis of cholesterol occur?
10% liver, 15% intestines
where in the cell does cholesterol biosynthesis occur, and from what substance is it synthesised?
cytoplasm and microsomes (from acetyl CoA)
What are the steps in cholesterol biosysthesis?
acetyl CoA HMG-CoA (HMG CoA reductase enzyme) mevalonate IPP Squalene cholesterol
What substance is produced by an intermediate to squalene in the cholesterol biosynthesis pathway?
CoQ10 (ubiquinone)
What is the major carrier of endogenously produced cholesterol?
LDL
How much cholesterol does LDL carry?
50%
