Biological Macromolecules: Carbohydrates, Lipids, Proteins, and Nucleic Acids

Vocabulary practice flashcards covering the elements, monomers, polymers, functions, and identification features of carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

A class of biological molecules composed of carbon, hydrogen, and oxygen (often in about a $1:2:1$ ratio) that provide quick energy, energy storage, and structural support (such as cellulose in plant cell walls).

D-Glucose

A six-carbon monosaccharide ($C_6H_{12}O_6$) shown in linear Fischer projection with an aldehyde group and in cyclic pyranose Haworth forms ($\alpha\text{-D-glucopyranose}$ and $\beta\text{-D-glucopyranose}$) formed via hemiacetal linkage.

Monosaccharide

The monomer building block of carbohydrates, such as glucose.

Polysaccharide

The polymer form of carbohydrates composed of linked monosaccharides, such as starch or cellulose.

Cellulose

A polysaccharide carbohydrate that provides structural support in plant cell walls.

Lipids

Biomolecules composed mainly of carbon, hydrogen, and oxygen (with phospholipids also containing phosphorus) that function in long-term energy storage, insulation, cell membranes, and hormones. They are not true polymers made from repeating monomers.

Triglyceride

A lipid composed of a glycerol molecule joined to three fatty acid chains (tails) characterized by many $\text{C}-\text{H}$ bonds.

Proteins

Biological macromolecules composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur; their functions include enzymes, transport, defense, movement, structure, and signaling.

Amino acid

The monomer of proteins, consisting of a central $\alpha\text{-carbon}$ bonded to a hydrogen atom, an amino group, a carboxylic acid group, and a variable side chain ($R$).

Polypeptide

The polymer form of proteins composed of amino acids joined together.

Peptide bond

The nitrogen-containing chemical bond ($-\text{CO}-\text{NH}-$) that links amino acid residues together in a polypeptide.

Nucleic acids

Biomolecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus that function to store and transmit genetic information, with RNA assisting in protein synthesis.

Nucleotide

The monomer unit of nucleic acids, consisting of a phosphate group, a 5-carbon sugar (such as deoxyribose), and a nitrogenous base (such as adenine).

DNA and RNA

The polymer forms of nucleic acids; DNA and RNA store and transmit genetic information, and RNA helps make proteins.

Macromolecule identification rules

Diagnostic structural visual cues: a sugar ring with many $-\text{OH}$ groups indicates a carbohydrate; long hydrocarbon chains indicate a lipid; nitrogen with amino acid/peptide structure indicates a protein; and phosphate combined with a sugar and a nitrogenous base indicates a nucleic acid.