Lipid anabolism Flashcards
What are the two main processes of lipid metabolism?
Lipid catabolism and lipid anabolism
These processes are not simple reversals of each other.
Where do most catabolic reactions and anabolic reactions occur in the cell?
Catabolic reactions occur in the mitochondrion; anabolic reactions occur in the cytosol.
What is the starting molecule for fatty acid biosynthesis?
Acetyl CoA
How is Acetyl CoA formed?
Through:
* Decarboxylation of pyruvate
* β-oxidation of fatty acids
* Degradation of certain amino acids
What inhibits the TCA cycle when ATP concentrations are high?
Isocitrate dehydrogenase is inhibited.
What happens to citrate when ATP concentrations are high?
Citrate concentration rises, activating the tricarboxylate transporter.
What is the Citrate Shuttle?
A transport mechanism that allows citrate to pass through mitochondrial membranes.
What is Malonyl CoA and its role in fatty acid biosynthesis?
Malonyl CoA is a key intermediate that blocks lipid catabolism and is rate limiting in fatty acid synthesis.
What are the components required for the reaction catalyzed by Acetyl CoA carboxylase?
Biotin carboxylase, biotin carrier protein, carboxyl transferase.
What is the function of ACP in fatty acid synthesis?
ACP is an acyl carrier protein that labels acetyl groups for fatty acid synthesis.
What occurs during the condensation stage of fatty acid synthesis?
Ketoacyl ACP synthase transfers an acetyl group from acetyl-ACP to malonyl-ACP, forming acetoacetyl-ACP.
What reducing agent is used in the reduction step of fatty acid synthesis?
NADPH
What is the final product of the fatty acid synthesis cycle?
Palmitoyl-ACP
What is the most common product of the fatty acid synthase complex in plants and animals?
Palmitate [CH3(CH2)14COO-].
Where do reactions introducing double bonds in fatty acids primarily occur?
Mainly in the endoplasmic reticulum (ER).
What are the essential fatty acids that mammals cannot synthesize?
Linoleate (C18:2D9,12) and Linolenate (C18:3D9,12,15).
What is the significance of omega-3 and omega-6 fatty acids?
Linoleate is omega (ω) 6; linolenate is omega (ω) 3.
Where does the glycerol part of acylglycerols typically originate from?
Glycerol 3-phosphate.
What are ketone bodies formed from?
The degradation of excess acetyl CoA from β-oxidation.
What condition leads to the formation of ketone bodies?
High intake of lipids and low intake of carbohydrates.
What is ketosis?
A condition characterized by high concentrations of acetoacetate and acetone in the blood.
How can ketone bodies be used during starvation?
As a fuel source by the brain in place of glucose.
What is ketoacidosis?
The lowering of blood pH due to high concentrations of acetoacetate and acetone.
