Lipids

• Lipids are biomolecules that contain fatty acids or a steroid nucleus.
• Liposomes are named for the Greek word lipos, which means “fat.”
• Lipids are soluble in organic solvents but not in water.
• Cholesterol is an important feature in cell membranes, fat-soluble vitamins, and steroid hormones.
• Lipids are biomolecules that contain fatty acids or a steroid nucleus.
• Cholesterol is an important feature in cell membranes, fat-soluble vitamins, and steroid hormones.
• Lipids are soluble in organic solvents but not in water.
• Lipids are biomolecules that contain fatty acids or a steroid nucleus, are soluble in organic solvents but not in water, and are named for the Greek word lipos, which means “fat.”
• Lipids are an important feature in cell membranes, fat-soluble vitamins, and steroid hormones.
• Facilitated transport uses protein channels to increase the rate of diffusion.
• Active transport moves ions against a concentration gradient.
• The transport of substances through cell membranes involves diffusion (passive transport), which moves particles from a higher to a lower concentration.
• Cell membranes have proteins and carbohydrates on the surface that communicate with hormones and neurotransmitters.
• Substances are transported across a cell membrane by diffusion (passive) transport, facilitated transport, or active transport.
• Types of lipids include triacylglycerols, waxes, glycerophospholipids, and sphingolipids, which are esters that can be hydrolyzed to give fatty acids and other molecules.
• Lipids are categorized based on function into Energy Storage (Triacylglycerols), Membrane structure (Phospholipids, Sphingoglycolipids, cholesterol), Emulsification (Bile acids), Messenger molecules (Steroid hormones; eicosanoids), and Protective coating (Biological waxes).
• Triacylglycerols and glycerophospholipids contain the alcohol glycerol.
• Sphingolipids contain the amino alcohol sphingosine.
• Steroids, which have a completely different structure, do not contain fatty acids and cannot be hydrolyzed, are characterized by the steroid nucleus of four fused carbon rings.
• Lipids are naturally occurring compounds in cells and tissues, are soluble in organic solvents but not in water, and are used in various applications such as energy storage, membrane structure, emulsification, messenger molecules, and protective coating.
• Essential Fatty Acids:Humans are capable of synthesizing some fatty acids from carbohydrates or other fatty acids, but cannot synthesize sufficient amounts of polyunsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid.
• Unsaturated fats such as those in vegetable oils and fish are recognized as more beneficial to health than saturated fats.
• Prostaglandins differ by the substituents attached to the five-carbon ring: prostaglandin E (PGE) has a ketone group on carbon 9, prostaglandin F (PGF) has a hydroxyl group on carbon 9.
• Waxes on the skin, fur, and feathers of animals provide a waterproof coating.
• Omega-3 fatty acids lower the tendency of blood platelets to stick together, reducing the possibility of blood clots.
• NSAIDs include naproxen (Aleve and Naprosyn), ketoprofen (Actron), and nabumetone (Relafen).
• In atherosclerosis and heart disease, cholesterol forms plaques that adhere to the walls of the blood vessels, causing blood pressure to rise and more plaque to form.
• Prostaglandins:Prostaglandins are hormone-like substances produced in small amounts in most cells, also known as eicosanoids, formed from arachidonic acid, a polyunsaturated fatty acid with 20 carbon atoms.
• Vegetables contain omega-6 acids, meaning the first double bond occurs at carbon 6 counting from the methyl end of the carbon chain.
• Fish have high levels of omega-3 acids, meaning the first double bond occurs at carbon 3, counting from the methyl end of the chain.
• Examples of omega-6 acids are linoleic and arachidonic acids.
• Examples of omega-3 acids include linolenic, eicosapentaenoic, and docosahexaenoic acids.
• Natural waxes are found on the surface of fruits and on the leaves and stems of plants, where they help prevent loss of water and damage from pests.
• When tissues are injured, arachidonic acid is converted to prostaglandins that produce inflammation and pain in the area.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) block production of prostaglandins, decreasing pain and inflammation.
• Saponification is the process of forming "soaps" (salts of fatty acids) and gives solid soaps that can be molded into different shapes when mixed with NaOH, and gives softer, liquid soaps when mixed with KOH.
• Hydrogen gas is bubbled through the heated oil typically in the presence of a nickel catalyst.
• Glycerophospholipids contain both polar and nonpolar regions that allow them to interact with polar and nonpolar substances, have a polar head containing the ionized amino alcohol and phosphate portion, which is strongly attracted to water, and have a nonpolar hydrocarbon tail portion soluble only in nonpolar substances such as lipids.
• Lecithin and cephalin are two types of glycerophospholipids that are abundant in brain and nerve tissues and found in egg yolk, wheat germ, peanuts, soybeans, and yeast.
• Phospholipids have a structure of two fatty acids chains + phosphate head, where the fatty acid chains are non-polar and hydrophobic, and the phosphate head is polar and hydrophilic, and they function to make up cell membranes (phospholipid bilayer).