Chapter 5 – The Structure and Function of Large Biological Molecules

Vocabulary flashcards covering major terms and definitions from Chapter 5 on biological macromolecules, including carbohydrates, lipids, proteins, nucleic acids, and related concepts.

Macromolecule

A huge biological molecule such as a carbohydrate, lipid, protein, or nucleic acid.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomer

A small, repeating unit that serves as the building block of a polymer.

Polymerization

The chemical process by which cells build polymers from monomers.

Enzyme

A specialized macromolecule (usually a protein) that speeds up a chemical reaction.

Condensation Reaction

A reaction in which two molecules are covalently bonded with the loss of a small molecule.

Dehydration Reaction

A condensation reaction in which the small molecule lost is water (−H and −OH).

Hydrolysis

The process that breaks bonds between monomers by adding a water molecule, reversing dehydration.

Carbohydrate

An organic molecule composed of carbon, hydrogen, and oxygen; includes sugars and polymers of sugars.

Monosaccharide

The simplest carbohydrate; a single sugar such as glucose.

Glucose

The most common monosaccharide (C6H12O6) central to cellular energy metabolism.

Disaccharide

A sugar formed by two monosaccharides joined by a glycosidic linkage.

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Sucrose

The most prevalent disaccharide, composed of glucose and fructose (table sugar).

Polysaccharide

A macromolecule made of hundreds or thousands of monosaccharides joined by glycosidic linkages.

Starch

A plant storage polysaccharide composed of glucose monomers.

Glycogen

An animal storage polysaccharide stored in liver and muscle cells.

Cellulose

A structural polysaccharide of plant cell walls; the most abundant organic compound on Earth.

Chitin

A structural polysaccharide with amino sugar monomers; found in arthropod exoskeletons and fungal cell walls.

Lipid

A class of large biological molecules that mix poorly with water; includes fats, phospholipids, and steroids.

Fat

A lipid composed of one glycerol molecule bonded to three fatty acids.

Glycerol

A three-carbon alcohol that forms the backbone of a fat molecule.

Fatty Acid

A carboxylic acid with a long hydrocarbon chain (usually 6–18 carbons).

Saturated Fatty Acid

A fatty acid with no carbon–carbon double bonds; saturated with hydrogen atoms; solid at room temperature.

Unsaturated Fatty Acid

A fatty acid with one or more carbon–carbon double bonds; liquid oils at room temperature.

Phospholipid

A lipid made of glycerol, two fatty acids, and a phosphate group; forms cell membranes.

Phospholipid Bilayer

A double layer of phospholipids that forms the basic structure of cell membranes.

Steroid

A lipid characterized by a carbon skeleton of four fused rings.

Cholesterol

An important steroid component of animal cell membranes and precursor to steroid hormones.

Protein

A biologically functional molecule made of one or more polypeptides folded into a specific 3-D shape.

Polypeptide

A polymer of amino acids linked by peptide bonds.

Amino Acid

An organic molecule with an amino group, a carboxyl group, a hydrogen atom, and an R group.

R Group (Side Chain)

The variable group of an amino acid that determines its unique properties.

Peptide Bond

The covalent bond between the carboxyl group of one amino acid and the amino group of another.

Denaturation

Loss of a protein’s native shape (and function) due to environmental conditions such as pH, salt, or heat.

Gene

A discrete unit of inheritance consisting of a specific nucleotide sequence in DNA.

Nucleic Acid

A polymer of nucleotides; DNA or RNA; stores and transmits hereditary information.

DNA (Deoxyribonucleic Acid)

A nucleic acid with deoxyribose sugar and bases A, T, C, G; usually double-stranded.

RNA (Ribonucleic Acid)

A nucleic acid with ribose sugar and bases A, U, C, G; usually single-stranded.

Nucleotide

The building block of nucleic acids; consists of a nitrogenous base, a pentose sugar, and one to three phosphate groups.

Nucleoside

A nitrogenous base bonded to a sugar, lacking phosphate groups.

Pyrimidine

A nitrogenous base with a single six-membered ring: cytosine, thymine, or uracil.

Purine

A nitrogenous base with a six-membered ring fused to a five-membered ring: adenine or guanine.

Deoxyribose

The five-carbon sugar in DNA nucleotides.

Ribose

The five-carbon sugar in RNA nucleotides.

Polynucleotide

A polymer of many nucleotides linked in a chain; forms DNA or RNA strands.

Sugar-Phosphate Backbone

The repeating pattern of sugar and phosphate groups in a nucleic acid strand.

Double Helix

The shape of DNA, consisting of two antiparallel polynucleotide strands coiled around an axis.

Antiparallel

Describes the opposite 5′ → 3′ orientations of the two strands in a DNA double helix.

Complementary Base Pairing

Specific hydrogen bonding between bases: A–T and G–C in DNA; A–U in RNA.

Gene Expression

The process by which information from DNA is used to synthesize RNA and protein.

Ribosome

The cellular organelle that is the site of protein synthesis.