Chapter 15: Lipids Practice Flashcards

Vocabulary-style flashcards covering the characteristics, classification, and chemical properties of lipids including fatty acids, triacylglycerols, steroids, and cell membrane transport.

Lipids

Biomolecules that are soluble in organic solvents but not in water, containing fatty acids or a steroid nucleus; named for the Greek word lipos, which means "fat".

Fatty Acids

Long, unbranched carbon chains with a carboxylic acid group at the end, typically $12-$ to $18-$carbon atoms long.

Saturated Fatty Acids

Fatty acids that contain only $C-C$ single bonds in the carbon chain, allowing them to fit close together in a regular pattern with higher melting points.

Monounsaturated Fatty Acids

Fatty acids containing only one $C=C$ double bond in the carbon chain.

Polyunsaturated Fatty Acids

Fatty acids containing at least two $C=C$ double bonds in the carbon chain.

Essential Fatty Acids

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

Prostaglandins (Eicosanoids)

Hormone-like substances formed from arachidonic acid ($20$ carbon atoms) that differ by substituents on a five-carbon ring and produce inflammation and pain when tissues are injured.

NSAIDs

Nonsteroidal anti-inflammatory drugs, such as aspirin, naproxen, and ketoprofen, that block the production of prostaglandins to decrease pain and inflammation.

Omega-3 Fatty Acids

Unsaturated fatty acids found in fish oil where the first double bond occurs at carbon $3$ counting from the methyl end of the chain.

Waxes

Esters of saturated fatty acids and long-chain alcohols, each containing from $14$ to $30$ carbon atoms, providing waterproof coatings for plants and animals.

Triacylglycerols (Triglycerides)

Esters of glycerol and three fatty acids that serve as the major form of energy storage for animals.

Hydrogenation

A reaction where hydrogen gas is bubbled through heated oil in the presence of a nickel catalyst to convert carbon–carbon double bonds into single bonds.

Trans Fatty Acids

Unsaturated fatty acids with bulky groups on opposite sides of the $C=C$ bond, often formed during hydrogenation, which behave like saturated fatty acids and raise $LDL$-cholesterol.

Saponification

The reaction of a fat with a strong base like $NaOH$ in the presence of heat to split triacylglycerols into glycerol and the sodium salts of fatty acids (soap).

Glycerophospholipids

Lipids containing two fatty acids forming ester bonds with the first and second hydroxyl groups of glycerol, and a phosphate group bonded to an amino alcohol.

Sphingomyelin

A phospholipid containing sphingosine instead of glycerol, an amide-bonded fatty acid, and a phosphoester bond to choline or ethanolamine; abundant in the myelin sheath.

Steroid Nucleus

A structural feature of steroids consisting of three cyclohexane rings and one cyclopentane ring fused together.

Cholesterol

The most important and abundant steroid in the body; synthesized in the liver and used for cell membranes, steroid hormones, and vitamin $D$.

Bile Salts

Substances synthesized from cholesterol in the liver and stored in the gallbladder that act like soaps to make fat soluble in water and aid in cholesterol absorption.

Lipoproteins

Water-soluble complexes that surround nonpolar lipids with polar lipids (glycerophospholipids) and proteins for transport to cells.

HDL (High-density Lipoprotein)

A type of lipoprotein that transports cholesterol between the tissues and the liver.

Steroid Hormones

Chemical messengers produced from cholesterol, including sex hormones (testosterone, estrogens) and adrenal corticosteroids (aldosterone, cortisone).

Fluid Mosaic Model

A model of cell membranes describing a lipid bilayer of phospholipids with proteins, carbohydrates, and cholesterol embedded within it.

Diffusion (Passive Transport)

The transport of substances across a cell membrane from a higher concentration to a lower concentration.

Active Transport

The transport of substances across a cell membrane that moves ions against a concentration gradient.