Lipids - CHEM 105

Comprehensive vocabulary flashcards covering the properties, classifications, and biological roles of lipids, including fatty acids, triacylglycerols, steroids, and cell membrane transport.

Lipids

Naturally occurring biomolecules that contain fatty acids or a steroid nucleus, which are soluble in organic solvents but not in water.

Steroids

Lipids that do not contain fatty acids and cannot be hydrolyzed; they are characterized by a steroid nucleus of four fused carbon rings.

Fatty acids

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

Saturated fatty acids

Fatty acids that contain only $C-C$ single bonds in the carbon chain, resulting in higher melting points and a regular pattern.

Monounsaturated fatty acids

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

Polyunsaturated fatty acids

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

Essential fatty acids

Polyunsaturated fatty acids, such as linoleic acid, linolenic acid, and arachidonic acid, that humans cannot synthesize in sufficient amounts and must obtain from their diet.

Prostaglandins

Hormone-like substances, also known as eicosanoids, formed from arachidonic acid that regulate functions like blood pressure and uterine muscle contraction.

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, commonly found in fish, 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, often used as waterproof coatings.

Triacylglycerols

Also known as triglycerides, these are esters of glycerol and three fatty acids and are the major form of energy storage for animals.

Fat

A lipid that is usually solid at room temperature and typically comes from animal sources such as meat, whole milk, butter, and cheese.

Oil

A lipid that is usually liquid at room temperature and is typically obtained from plant sources like corn, cottonseed, or olives.

Hydrogenation

The reaction of unsaturated fatty acids with hydrogen gas ($H_2$), typically using a nickel ($Ni$) catalyst, to produce carbon-carbon single bonds.

Trans fatty acids

Unsaturated fatty acids with bulky groups on opposite sides of the $C=C$ bond, which can form as side products during commercial hydrogenation and raise LDL-cholesterol.

Saponification

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

Phospholipids

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

Glycerophospholipids

Lipids containing two fatty acids forming ester bonds with glycerol, and a phosphate group bonded to an amino alcohol.

Sphingomyelin

A type of phospholipid that contains sphingosine instead of glycerol, found abundantly in the white matter of the myelin sheath.

Steroid nucleus

A structure consisting of three cyclohexane rings and one cyclopentane ring fused together, designated as rings A, B, C, and D.

Cholesterol

The most important and abundant steroid in the body; it is used for cell membranes and hormone synthesis but can clog arteries when levels are high.

Bile salts

Steroids synthesized in the liver from cholesterol and stored in the gallbladder that act like soaps to make fats soluble in water.

Lipoproteins

Water-soluble complexes formed by nonpolar lipids, glycerophospholipids, and proteins used to transport lipids through the blood.

Steroid hormones

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

Anabolic steroids

Derivatives of testosterone used illegally to increase muscle mass, which can cause side effects like liver damage and fluid retention.

Adrenal corticosteroids

Hormones produced by the adrenal glands, such as aldosterone (electrolyte balance) and cortisone (glucose regulation).

Fluid mosaic model

A model of cell membrane structure describing a lipid bilayer of phospholipids with embedded proteins, carbohydrates, and cholesterol.

Diffusion (passive transport)

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

Facilitated transport

The movement of substances across a cell membrane through protein channels to increase the rate of diffusion.

Active transport

The movement of ions across a cell membrane against a concentration gradient.