Lipids

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Lipid Noun

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[lip-id]

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Lipid

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A class of biomolecules including fats, oils, and waxes that are non-polar and insoluble in water.

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Example: This image shows a phospholipid, a type of lipid. It has a water-loving (hydrophilic) head and water-fearing (hydrophobic) tails, causing them to form a bilayer.

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Hydrophobic Adjective

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[hy-dro-fo-bik]

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Hydrophobic

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The property of a substance to repel or fail to mix with water, meaning it is 'water-hating'.

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Example: This diagram attempts to show a lipid molecule, labeling the water-fearing (hydrophobic) part, but incorrectly calls the hydrophobic tails a 'head'.

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Fatty Acid Noun

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[fat-ee as-id]

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Fatty Acid

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A building block of lipids, consisting of a long hydrocarbon chain and a carboxyl group at one end.

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Example: This diagram shows the structure of a fatty acid, which is a long chain of carbon and hydrogen atoms with a special 'carboxyl group' at one end.

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Glycerol Noun

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[glis-er-ol]

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Glycerol

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A three-carbon alcohol molecule that serves as the backbone for triglycerides and phospholipids.

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Example: This image shows the chemical structure of a glycerol molecule, which has a three-carbon backbone with a hydroxyl (-OH) group attached to each carbon.

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Saturated Fatty Acid Noun

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[sach-uh-ray-tid fat-ee as-id]

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Saturated Fatty Acid

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A type of fatty acid in which all carbon-carbon bonds are single bonds, making it saturated with hydrogen atoms.

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Example: This diagram shows a saturated fatty acid molecule, where the long carbon chain is 'saturated' with hydrogen atoms and has no double bonds.

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Unsaturated Fatty Acid Noun

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[un-sach-uh-ray-tid fat-ee as-id]

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Unsaturated Fatty Acid

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A type of fatty acid that contains at least one double bond in its hydrocarbon chain.

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Example: This diagram shows an unsaturated fatty acid has at least one carbon-carbon double bond (C=C) in its chain, which creates a 'kink' or bend.

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Triglyceride Noun

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[try-glis-er-ide]

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Triglyceride

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The most common type of fat in food and the body, consisting of a glycerol molecule attached to three fatty acids.

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Example: This diagram shows a triglyceride molecule is made of two parts: one glycerol 'backbone' (in blue) and three fatty acid 'tails' (in pink).

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Ester Bond Noun

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[es-ter bond]

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Ester Bond

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The chemical bond that links a fatty acid to a glycerol molecule, formed in a condensation reaction.

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Example: This diagram shows how an ester bond is formed when a fatty acid molecule joins with a glycerol molecule, releasing a water molecule in the process.

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Phospholipid Noun

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[fos-fo-lip-id]

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Phospholipid

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A lipid with a hydrophilic phosphate head and two hydrophobic fatty acid tails, a primary component of cell membranes.

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Example: A phospholipid is a lipid with a water-loving (hydrophilic) head and a water-fearing (hydrophobic) tail, which arrange themselves into a bilayer.

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Sterol Noun

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[steer-ol]

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Sterol

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A type of lipid characterized by a specific four-ring carbon structure, with cholesterol being a well-known example.

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Example: This diagram shows two types of sterols, a kind of lipid, inside a blood vessel: cholesterol (from animals) and plant sterols (from plants).