Ch 3 MACROMOLECULES - Vocabulary Flashcards

Vocabulary flashcards covering macromolecules (lipids, carbohydrates, nucleic acids, proteins), their monomers, structures, and essential functions.

Macromolecule

A large biological molecule such as a lipid, carbohydrate, nucleic acid, or protein; typically built from smaller units (monomers) joined by covalent bonds.

Polymer

A large molecule composed of many repeating monomers; carbohydrates, nucleic acids, and proteins are polymers.

Monomer

A small molecule that can join with others to form a polymer.

Triglyceride

A lipid with three fatty acids attached to glycerol; major form of energy storage.

Fatty acid

A long hydrocarbon chain with a terminal carboxyl group; can be saturated or unsaturated.

Saturated fatty acid

A fatty acid with only single C–C bonds; straight chains that pack tightly, often solid at room temperature.

Unsaturated fatty acid

A fatty acid containing one or more C=C double bonds; kinks prevent tight packing and lower melting point.

Phospholipid

A lipid with two fatty acids and a phosphate-containing head; amphipathic and a key component of membranes.

Amphipathic

Having both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Lipid bilayer

Two-layer sheet of phospholipids that forms the core structure of cell membranes.

Lipoprotein

A complex of lipids and proteins that transports lipids in the bloodstream.

Carbohydrate

Macromolecule made of carbon, hydrogen, and oxygen; often a source of energy and structural material.

Monosaccharide

Simple sugar (pentose or hexose) that can exist in linear or ring form.

Disaccharide

Two monosaccharides linked by a glycosidic bond; examples include sucrose, maltose, and cellobiose.

Glycosidic bond

Covalent bond that links monosaccharides; can be alpha or beta and occur at various carbon positions.

Polysaccharide

Large carbohydrate polymer made of many monosaccharide units; used for storage or structure.

Cellulose

Structural polysaccharide in plants; beta-1,4 linked glucose units, unbranched and very strong.

Starch

Plant storage polysaccharide; mainly alpha-1,4 links with occasional alpha-1,6 branching.

Glycogen

Animal storage polysaccharide; highly branched alpha-1,4 and alpha-1,6 linkages, highly soluble.

Chitin

Structural polysaccharide in arthropods; polymer of modified glucose with 1,4 linkages.

Nucleic acid

DNA or RNA; polymers that store, transmit, and express genetic information.

Nucleotide

Nucleic acid monomer comprising a sugar (ribose or deoxyribose), a base, and one to three phosphate groups.

Purine

A double-ring nitrogenous base (A and G) found in DNA and RNA.

Pyrimidine

A single-ring base (C, T in DNA; C, U in RNA).

DNA

Deoxyribonucleic acid; usually double-stranded, antiparallel, uses bases A, T, C, G and deoxyribose sugar.

RNA

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

Phosphodiester bond

Bond linking nucleotides between the 3′-OH of one sugar and the 5′-phosphate of the next.

Base pairing

Hydrogen-bonding rules: A pairs with T (or U in RNA); C pairs with G; strands are antiparallel.

Protein

Macromolecule composed of amino acids; performs most cellular functions.

Amino acid

Amino acid monomer with an amino group, a carboxyl group, and a variable R group.

Peptide bond

Covalent bond linking amino acids during protein synthesis via a condensation reaction.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Regular folding patterns such as alpha helices and beta pleated sheets stabilized by hydrogen bonds.

Tertiary structure

Three-dimensional folding of a single polypeptide, including a hydrophobic core and surface interactions.

Quaternary structure

Arrangement of two or more polypeptide subunits into a functional protein.

Disulfide bridge

Covalent S–S bond between cysteine residues that stabilizes protein structure.

Denaturation

Loss of native protein structure due to heat, pH, or chemicals; primary structure may remain intact.

Cofactor

Nonprotein component required for enzyme activity (inorganic ions or organic molecules).

Coenzyme

Loosely bound organic cofactor that participates in enzyme-catalyzed reactions.

Prosthetic group

Covalently bound cofactor permanently associated with a protein.

Enzyme

Protein catalyst that speeds up a biochemical reaction by lowering activation energy.