Key Concepts of Biological Macromolecules to Know for AP Biology

Biological macromolecules are essential for life, made up of carbohydrates, lipids, proteins, and nucleic acids. Each type plays a unique role in energy storage, structure, and function, forming the foundation of all living organisms and their processes.

1. Carbohydrates

   • Composed of carbon, hydrogen, and oxygen, typically in a 1:2:1 ratio.
   • Serve as a primary energy source for living organisms (e.g., glucose).
   • Can be classified into monosaccharides (simple sugars), disaccharides (two sugars), and polysaccharides (many sugars).
   • Play key roles in cell structure and signaling (e.g., cellulose in plants, glycoproteins in cell membranes).
   • Important for energy storage (e.g., starch in plants, glycogen in animals).

2. Lipids

   • Hydrophobic molecules primarily made of long hydrocarbon chains or rings.
   • Include fats, oils, phospholipids, and steroids, each with distinct functions.
   • Serve as long-term energy storage, insulation, and protection for organs.
   • Form cell membranes (phospholipids) and are involved in signaling (steroids like hormones).
   • Important for maintaining cellular structure and fluidity.

3. Proteins

   • Composed of amino acids linked by peptide bonds, forming polypeptide chains.
   • Serve as enzymes, structural components, transport molecules, and antibodies.
   • The sequence and structure of amino acids determine protein function (primary, secondary, tertiary, and quaternary structures).
   • Involved in nearly every biological process, including metabolism, immune response, and cell signaling.
   • Can be denatured by changes in temperature or pH, affecting their functionality.

4. Nucleic acids

   • Composed of nucleotides, which include a sugar, phosphate group, and nitrogenous base.
   • Two main types: DNA (stores genetic information) and RNA (involved in protein synthesis).
   • DNA's double helix structure allows for replication and transmission of genetic information.
   • RNA plays a crucial role in translating genetic information into proteins (mRNA, tRNA, rRNA).
   • Essential for heredity, gene expression, and regulation of cellular activities.