Metabolic pathways: lipid anabolism Flashcards
When are new fatty acids created?
When the body obtains more energy than is needed - dietary energy is converted into stored fat
Where does lipogenesis occur?
Mainly liver, but also kidney, mammary glands, brain, adipose tissue
How is free fatty acid transported in the blood?
Bound to albumin
What precursor does synthesis of new fatty acids begin with?
Acetyl-CoA
Where does acetyl-CoA for fatty acid synthesis come from?
From dietary carbohydrate - pyruvate dehydrogenase complex
From fat beta oxidation
How is acetyl-CoA transported from the mitochondrial membrane to the cytoplasm?
Linked to oxaloacetate to form citric acid
When citric acid concentration becomes greater inside the mitochondrial membrane than out, it can be transported into the cytoplasm
What must be done to acetyl-CoA before it can be converted to fatty acids?
Activated to malonyl-CoA
Through which enzyme is the activation of acetyl-CoA to malonyl-CoA achieved?
Acetyl-CoA carboxylase, the main regulatory enzyme in this pathway
What does acetyl-CoA carboxylase do?
Adds an additional carbon group to acetyl-CoA, converting it to malonyl-CoA
How many ATP does it take to convert acetyl-CoA to malonyl-CoA
1 ATP
What does fatty acid synthase do?
Catalyses synthesis of saturated long chain fatty acids from malonyl-CoA, acetyl-CoA and NADPH
What is the structure of fatty acid synthase?
A dimer consisting of two identical polypeptide chains with seven distinct enzyme activities
Which protein on the fatty acid synthase carries the growing fatty acid chain during synthesis?
Acyl-carrier protein (ACP)
Which precursor, malonyl-CoA or acetyl-CoA, donates carbons to be added to the growing fatty acid chain?
Malonyl-CoA
How many carbons are added to the acyl chain with each cycle?
2
