Lipid/fatty synthesis Flashcards
What defines a lipid?
Lipids are generally water-insoluble, hydrophobic molecules. They can also be amphipathic, containing both polar and non-polar regions.
What are the main types of fatty acids?
Saturated: No C=C bonds. Unsaturated: At least one C=C bond; includes monounsaturated (1 C=C) and polyunsaturated (>1 C=C).
What are essential fatty acids?
Linoleate (18:2 ∆9,12) and Linolenate (18:3 ∆9,12,15) cannot be synthesized by the body.
What are triacylglycerols?
Molecules with three fatty acyl residues joined to glycerol. Serve as energy storage and form fat droplets in cells.
What are fatty acid derivatives used for?
Prostaglandins, thromboxanes, and leukotrienes act as chemical mediators in inflammation and clotting.
What is ATP and its primary function?
ATP (adenosine triphosphate) is the universal energy currency in cells. Drives metabolism by shifting equilibrium in unfavorable reactions.
What makes ATP energy-rich?
The presence of two phosphoanhydride bonds, which release significant energy upon hydrolysis.
What is the ATP-ADP cycle?
ATP is hydrolyzed to ADP and AMP, releasing energy. Regeneration of ATP from ADP ensures a continuous energy supply.
What enzymes interact with ATP?
Kinases: Add phosphate groups. Phosphatases: Remove phosphate groups.
How much ATP is turned over daily?
Approximately 40 kg per day, with higher rates during exercise.
What are carbohydrates?
Biological molecules with the general formula Cn(H2O)n. Serve structural (e.g., cellulose) and energy roles (e.g., glycolysis).
What are monosaccharides?
Simple sugars like glucose, galactose, and fructose. Classified by the number of carbons: triose (3), pentose (5), hexose (6).
What is a condensation reaction?
The process where two monosaccharides combine, losing a water molecule, to form disaccharides.
What is stereochemistry in carbohydrates?
Chirality of sugars influences enzyme recognition. D-sugars are naturally occurring; L-sugars are rare.
What is the significance of anomeric carbons?
The orientation (alpha or beta) of the hydroxyl group at the anomeric carbon determines sugar properties.
What are diastereoisomers and enantiomers?
Enantiomers: Mirror images, not superimposable (e.g., D-glucose and L-glucose). Diastereoisomers: Differ at multiple chiral centers but are not mirror images.
What are the roles of aldohexoses and ketohexoses?
Aldohexoses (e.g., glucose) contain an aldehyde group. Ketohexoses (e.g., fructose) contain a ketone group.
What are the key intermediates in triacylglycerol and phospholipid synthesis?
Phosphatidate is the intermediate in both pathways.
What is the process of sphingolipid synthesis?
Begins with serine and palmitoyl-CoA forming 3-ketosphinganine. Reduced to sphinganine, then converted to ceramide (precursor for all sphingolipids).
How is cholesterol synthesized?
All carbon atoms derive from acetyl CoA. Pathway involves conversion of acetyl CoA to isopentyl diphosphate, then squalene, and finally cholesterol.
What regulates cholesterol synthesis?
HMG-CoA reductase, regulated by phosphorylation, transcription, and cholesterol levels. Statins act as competitive inhibitors of this enzyme.
Where does fatty acid synthesis occur?
In the cytosol of liver cells and adipocytes.
What are the key steps in fatty acid synthesis?
Initiation: Formation of acetyl ACP and malonyl ACP. Elongation: Adding two-carbon units from malonyl ACP to a growing chain.
What is β-oxidation?
A pathway that removes two-carbon units as acetyl CoA. Occurs in mitochondria and involves activation by coenzyme A.
