Classes of Lipids Flashcards
What are lipids?
Lipids are organic molecules that are insoluble in water but soluble in organic solvents. They include nonglyceride lipids (waxes, sphingolipids, steroids), fatty acids, glycerides (triglycerides, phospholipids), and complex lipids (lipoproteins).
How do lipids interact with each other?
Lipids interact via weak Van der Waals forces, which arise from temporary dipoles created by fluctuations in electron density. These forces lead to attractions between long hydrocarbon chains.
What causes hydrophobic intermolecular forces in lipids?
Hydrophobic forces arise from the tendency of nonpolar molecules to avoid contact with water, leading to the aggregation of hydrophobic molecules in aqueous solutions to minimize water interaction.
What characterizes saturated fatty acids?
Saturated fatty acids have no double bonds between carbon atoms, contain an even number of carbon atoms, and their melting temperature increases with chain length due to stronger Van der Waals attractions.
What are short-chain fatty acids and their sources?
SCFAs include acetic, propanoic, and butyric acids, which are volatile fatty acids produced during bacterial fermentation of carbohydrates, particularly dietary fiber, in the colon.
What are medium-chain fatty acids, and where are they found?
MCFAs include caproic, caprylic, capric, and lauric acids, found in palm kernel and coconut oils, as well as in milk fat from cows, sheep, and goats.
How do MCFAs and LCFAs differ in absorption?
MCFAs are absorbed directly into the portal vein and transported to the liver, while LCFAs are reesterified into triglycerides and enter lymphatic circulation as chylomicrons.
What are long-chain fatty acids and their classification?
LCFAs have carbon chains longer than 12 carbon atoms, with palmitic and stearic acids being the most common. They can be classified as very long-chain fatty acids (VLCFAs) if longer than 22 carbons.
What defines unsaturated fatty acids?
Unsaturated fatty acids have one or more double bonds in their structure, which can create kinks in the aliphatic chain, affecting their physical properties.
What is the significance of the cis configuration in unsaturated fatty acids?
The cis configuration, where hydrogens are on the same side of the double bond, prevents tight packing, resulting in lower melting points and liquid states at room temperature.
What are trans fatty acids, and why are they considered undesirable?
Trans fatty acids have a specific geometric configuration that increases the risk of heart disease and other health issues. They were primarily found in partially hydrogenated oils, which are now banned in many regions.
What enzymes are involved in the desaturation of fatty acids?
Stearoyl-CoA desaturase-1 (Δ9 desaturase) is responsible for converting saturated fatty acids like palmitic and stearic acids into monounsaturated fatty acids.
What are some health benefits associated with unsaturated fatty acids?
Unsaturated fatty acids can improve heart health, reduce inflammation, and lower the risk of chronic diseases such as cardiovascular disease and diabetes.
What process do fatty acids undergo for energy production?
Fatty acids undergo β-oxidation in the mitochondria, which cleaves acyl chains to produce acetyl-CoA, entering the citric acid cycle for ATP production
What are lipoproteins, and what is their function?
Lipoproteins are complexes of lipids and proteins that transport lipids in the bloodstream, playing a crucial role in lipid metabolism and distribution.
