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Biological macromolecules review

Key terms

Biological macromoleculeA large, organic molecule such as carbohydrates, lipids, proteins, and nucleic acids.
MonomerA molecule that is a building block for larger molecules (polymers). For example, an amino acid acts as the building blocks for proteins.
PolymerA large molecule made of repeating subunits (monomers). For example, a carbohydrate is a polymer that is made of repeating monosaccharides.

Types of biological macromolecules

Biological macromoleculeBuilding blocksFunctionsExamples
CarbohydratesMonosaccharides (simple sugars)Provide cells with quick/short-term energy, source of dietary fiberGlucose, sucrose, starch, cellulose, chitin
LipidsFatty acids and glycerolProvide cells with long-term energy, make up biological membranesFats, phospholipids, waxes, oils, grease, steroids
ProteinsAmino acidsProvide cell structure, send chemical signals, speed up chemical reactions, etcKeratin (found in hair and nails), hormones, enzymes, antibodies
Nucleic acidsNucleotidesStore and pass on genetic informationDNA, RNA

Common mistakes and misconceptions

  • Describing macromolecules as “large” is relative. We refer to them as “macro” because they are large compared to other, smaller molecules. However, this does not mean that they are large enough to view with the naked eye. Even a large protein, like hemoglobin, is still a million times smaller than a grain of rice!
  • Not all fats and carbohydrates are “bad.” Information about different kinds of diets can be confusing and may lead someone to believe that all fats or all carbohydrates are unhealthy. This simply isn’t the case. Fats and carbohydrates are actually essential for cellular function!

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