Summary
Highlights
Macromolecules are large structures essential for all living organisms, built from smaller units called monomers that bind to form polymers. There are four main classes: carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates serve as the main fuel source and structural components for many plants. Their monomers are monosaccharides (simple sugars like glucose), and their polymers are polysaccharides (long chains of monosaccharides). Examples include starch and glycogen for energy storage, and cellulose and chitin for structure.
Lipids are a diverse group of hydrophobic molecules with functions including energy storage, cell membrane formation, and steroid functions. Unlike other macromolecules, they don't have true monomers. Examples include triglycerides (fats), phospholipids (for cell membranes), and steroids (like sex hormones, based on cholesterol).
Proteins are crucial for nearly all cellular functions. Their monomers are amino acids (20 different types), and their polymers are polypeptides. The specific folding of a protein determines its function.
Nucleic acids are responsible for storing, transmitting, and expressing genetic information. Their monomers are nucleotides (like adenine, guanine, and thymine), which form polymers called polynucleotides, such as DNA and RNA.