Lipids Flashcards

Flashcards about Lipids

Lipids

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.”

Waxes, fats, oils, and phospholipids

Lipids that are esters that can be hydrolyzed to give fatty acids and other molecules.

Steroids

Lipids that do not contain fatty acids and cannot be hydrolyzed, characterized by the steroid nucleus of four fused carbon rings.

Fatty acids

Long, unbranched carbon chains with a carboxylic acid group at the end, typically 12– to 18–carbon atoms long, and insoluble in water because of the long carbon chain.

Saturated fatty acids

Fatty acids that do not contain C C double bonds in the carbon chain.

Unsaturated fatty acids

Fatty acids that contain C C double bonds in the carbon chain.

Monounsaturated fatty acids (MUFA)

Fatty acids that contain one carbon-carbon double bond.

Polyunsaturated fatty acids (PUFA)

Fatty acids that contain more than one carbon-carbon double bond.

Essential fatty acids

Polyunsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid that must be obtained from the diet because humans cannot synthesize sufficient amounts.

Eicosanoids

A group of compounds derived from 20- carbon unsaturated fatty acids (eicosanoic acids) and synthesized throughout the body that function as short-lived chemical messengers that act near their points of synthesis (“local hormones”).

Prostaglandins

Hormone-like substances produced in cells, also known as eicosanoids, formed from arachidonic acid, a polyunsaturated fatty acid with 20 carbon atoms, differing by the substituents attached to the five-carbon ring, and having many functions, such as lowering or raising blood pressure and stimulating contraction and relaxation of the smooth muscle of the uterus.

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Drugs that block the production of prostaglandins, decreasing pain and inflammation.

Triacylglycerols (triglycerides)

Esters of glycerol (a trihydroxy alcohol) and fatty acids that are formed when three hydroxyl groups of glycerol react with the carboxyl groups of three fatty acids and are named by changing glycerol to glyceryl and naming the fatty acids as carboxylates.

Hydrogenation

Reactions in which double bonds in unsaturated fatty acids react with hydrogen gas to produce carbon–carbon single bonds, typically using a nickel catalyst.

Hydrolysis

A reaction in which triacylglycerols split into glycerol and three fatty acids, requiring a strong acid, HCl or H2SO4, or digestive enzymes called lipases.

Saponification

The reaction of a fat with a strong base such as NaOH in the presence of heat, splitting triacylglycerols into glycerol and the sodium salts of fatty acids to form soaps.

Micelle

A spherical cluster formed by the aggregation of soap or detergent molecules so that their hydrophobic ends are in the center and their hydrophilic ends are on the surface.

Phospholipids

A family of lipids similar in structure to triacylglycerols, including glycerophospholipids and sphingomyelin.

Glycerophospholipids

Phospholipids that contain two fatty acids that form ester bonds with the first and second hydroxyl groups of glycerol and a hydroxyl group that forms an ester with phosphoric acid, which forms another phosphoester bond with an amino alcohol.

Sphingomyelin

A phospholipid that contains sphingosine instead of glycerol and contains a fatty acid, phosphate, and an amino alcohol.

Lecithin and cephalin

Types of glycerophospholipids that are abundant in brain and nerve tissues and are found in egg yolk, wheat germ, and yeast.

Glycolipids

Sphingosine derivatives which contain no phosphate group but have an attached carbohydrate that is a monosaccharide or a short chain of monosaccharides (an oligosaccharide).

Steroid nucleus

Consists of three cyclohexane rings and one cylopentane ring, fused together, with rings designated as A, B, C, and D, numbered carbon atoms beginning in ring A, and two methyl groups at positions 18 and 19.

Cholesterol

The most important and abundant steroid in the body, obtained from meats, milk, and eggs, synthesized in the liver, and needed for cell membranes, brain and nerve tissue, steroid hormones, and vitamin D.

Bile salts

Synthesized in the liver from cholesterol and stored in the gallbladder; have polar and nonpolar regions that act like soaps to make fat soluble in water.