Flashcards in Lipids 3 Deck (25)
Where does fatty acid synthesis occur?
lactating mammary gland
What are fatty acids synthesised from?
from acetyl CoA derived from excess protein, fat and carbohydrate
What part of the cell does fatty acid synthesis occur in?
Acetyl CoA is formed in the matrix of the mitochondrion and so has to be transferred out into the cytosol. How does this occur?
via the citrate shuttle when citrate concentration in mitochondrion is high
What 2 enzymes are required for fatty acid synthesis?
Acetyl CoA carboxylase (activation/regulation)
Fatty acid synthase (multifunctional enzyme)
What is required for fatty acid synthesis?
acetyl CoA and NADPH
What is produced from fatty acid synthesis?
What does acetyl CoA carboxylase do?
forms Malonyl CoA by adding CO2 to acetyl CoA which is the committed step in fatty acid synthesis
What are the key regulators of the activity of acetyl CoA carboxylase?
activated by citrate (signals that there is enough glucose)
deactivated by palmitoyl CoA
glucagon and epinephrine deactivate
What happens in elongation of malonyl coA?
Acetoacyl-ACP is formed from Acyl-malonyl ACP condensing
What is acetoacetyl-ACP?
complex of acyl-malonyl and ACP enzyme
What happens to the acetoacyl-ACP?
carbons are added 2 at a time with the enemy acting as an 'arm' sweeping to pick up these carbons. Palmityl-ACP is formed
What does thioesterase do?
cleaves palmityl CoA from the ACP
What does the multifuctional fatty acid synthase enzyme do?
Works with the ACP to catalyse the formation of long chain fatty acids.
Is a series of 7 enzymes that the ACP arm swings the acyl-malonyl round to catalyse reactions to extend the chain
How much NADPH is required for the formation of palmitate and where do we get the NADPH?
from the pentose phosphate pathway
Where does any extra modification of palmitate or dietary fatty acids occur?
in mitochondria and ER by diverse enzymes
What are steroid hormones?
chemical substances that serve as chemical messengers in the body
What is the starting material for the formation of steroid hormones?
What are eicosanoids?
signalling molecules derived from 20 carbon unsaturated fatty acids (omega 3) and are synthesised throughout the body
What is the function of cholesterol?
component of cell membranes
precursor to other substances e.g. sterol hormones, vitamin D, bile acids
Where is cholesterol made?
mainly in the liver
What do statins do?
inhibit enzyme responsible for cholesterol synthesis and lower LDL levels
What do eicosanoids regulate?
pain and fever
blood clot induction
sleep/wake cycle etc
What are COX inhibitors?
anti-inflammatory and fever-reducing property due to inhibition of COX1 enzyme and prostaglandin synthesis