Chapter 5: The Structure and Function of Large Biological Molecules

Vocabulary flashcards covering key terms about macromolecules, especially polymers, carbohydrates, lipids, and basic protein-related concepts from Chapter 5.

Macromolecule

A very large molecule formed by linking together smaller units (monomers); the four major classes are carbohydrates, lipids, proteins, and nucleic acids.

Polymer

A long molecule consisting of many similar building blocks (monomers) covalently bonded together.

Monomer

A small molecule that can join with others to form polymers.

Dehydration reaction

A condensation reaction where two monomers bond with the loss of a water molecule; often enzyme-catalyzed.

Hydrolysis

A reaction that breaks polymers into monomers by adding a water molecule.

Monosaccharide

A simple sugar; a basic unit of carbohydrates, typically with molecular formula a multiple of CH2O.

Aldose

A monosaccharide with an aldehyde group.

Ketose

A monosaccharide with a ketone group.

Hexose

A six-carbon monosaccharide (e.g., glucose, fructose).

Pentose

A five-carbon monosaccharide.

Triose

A three-carbon monosaccharide.

Disaccharide

A carbohydrate formed when two monosaccharides are joined by a glycosidic linkage.

Polysaccharide

A polymer of many sugar building blocks; serves storage or structural roles.

Starch

A storage polysaccharide in plants; consists of glucose monomers, primarily used for energy storage.

Glycogen

An animal storage polysaccharide; highly branched glucose polymer stored mainly in liver and muscle.

Cellulose

A structural polysaccharide in plant cell walls; glucose monomers linked by beta (β) 1→4 glycosidic bonds.

Chitin

A structural polysaccharide found in arthropod exoskeletons and in some fungi cell walls.

Lipid

A diverse group of hydrophobic molecules; do not form polymers; include fats, phospholipids, and steroids.

Fat

A triacylglycerol formed from glycerol and three fatty acids; a major energy storage molecule.

Glycerol

a three-carbon molecule with three hydroxyl (-OH) groups that serves as the backbone for fats and phospholipids in biological systems.

Fatty acid

A carboxyl group attached to a long hydrocarbon chain; varies in length and degree of unsaturation.

Ester linkage

Bond formed between glycerol and a fatty acid during fat synthesis.

Triacylglycerol

Another name for a fat molecule; three fatty acids esterified to glycerol.

Saturated fatty acid

Fatty acid with no double bonds between carbon atoms; maximum hydrogen; typically solid at room temperature.

Unsaturated fatty acid

Fatty acid with one or more double bonds; kinks the chain (often cis); usually liquid at room temperature.

Macromolecule

A very large molecule formed by linking together smaller units (monomers); the four major classes are carbohydrates, lipids, proteins, and nucleic acids.

Polymer

A long molecule consisting of many similar building blocks (monomers) covalently bonded together.

Monomer

A small molecule that can join with others to form polymers.

Dehydration reaction

A condensation reaction where two monomers bond with the loss of a water molecule; often enzyme-catalyzed.

Hydrolysis

A reaction that breaks polymers into monomers by adding a water molecule.

Glycosidic linkage

A covalent bond formed between two monosaccharides during dehydration (removal of water), linking their sugar units.

Monosaccharide

A simple sugar; a basic unit of carbohydrates, typically with molecular formula a multiple of CH2O (e.g., glucose).

Hexose

A six-carbon monosaccharide (e.g., glucose, fructose).

Pentose

A five-carbon monosaccharide.

Triose

A three-carbon monosaccharide.

Sucrose

A disaccharide composed of glucose and fructose.

Maltose

A disaccharide composed of two glucose units.

Alpha-glucose

The form of glucose used in starch; has \alpha ring orientation in the glycosidic linkage.

Beta-glucose

The form of glucose used in cellulose; has \beta ring orientation in the glycosidic linkage.

Lipid

A diverse group of hydrophobic molecules; do not form polymers; include fats, phospholipids, and steroids.

What are the four major classes of biological macromolecules?

Carbohydrates, Lipids, Proteins, and Nucleic acids.

Compare saturated and unsaturated fatty acids.

Saturated fatty acids have no double bonds between carbons and are usually solid at room temperature. Unsaturated fatty acids have one or more double bonds and are usually liquid at room temperature.

Compare cis and trans fats.

Cis fats have hydrogens on the same side of the double bond, resulting in a bent molecular shape. Trans fats have hydrogens on opposite sides of the double bond, resulting in a straighter chain.

Primary structure of protein

The unique sequence of amino acids in a polypeptide chain.

Secondary structure of protein

Local folding patterns, such as alpha helices (\alpha-helices) or beta-pleated sheets (\beta-pleated sheets), stabilized by hydrogen bonds between the polypeptide backbone atoms.

Tertiary structure of protein

The overall three-dimensional shape of a single polypeptide chain, resulting from interactions between the R-groups of amino acids (e.g., hydrophobic interactions, ionic bonds, disulfide bridges).

Quaternary structure of protein

The complex formed by the association of multiple polypeptide subunits (e.g., hemoglobin, which consists of four polypeptide chains).

Pyrimidines

Nitrogenous bases with a single-ring structure; includes cytosine (C), thymine (T) in DNA, and uracil (U) in RNA.

Purines

Nitrogenous bases with a double-ring structure; includes adenine (A) and guanine (G).

Distinguish between a nucleotide and a nucleoside.

A nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups. A nucleoside consists only of a nitrogenous base and a pentose sugar (no phosphate).

Compare ribose and deoxyribose sugars.

Ribose is the sugar found in RNA and has a hydroxyl (–OH) group at the 2′ carbon atom. Deoxyribose is the sugar found in DNA and has an hydrogen (–H) atom at the 2′ carbon (lacking an oxygen atom).

5′ end of a nucleic acid strand

The end of a nucleic acid strand that has a phosphate group attached to the 5′ carbon of the sugar.

3′ end of a nucleic acid strand

The end of a nucleic acid strand that has a free hydroxyl (–OH) group attached to the 3′ carbon of the sugar.