# Macromolecules: What We're Made Of --- **Macromolecules** are essential components for sustaining [[biology|life]]. They are present in every living thing. As their name suggests, they are very large as molecules go. There are four different classes of macromolecules: - [[nucleic acid|Nucleic acids]] are polymers of nucleotides, and make up DNA and RNA. - [[protein|Proteins]] are polymers of amino acids, and are incredibly complex and varied in their composition and function. - [[Carbohydrates]] are polymers of monosaccharides, and they are important for energy storage. - [[Lipids]] are polymers of two or more fatty acids attached to a glycerol molecule. They are important for energy storage, and chemical messaging. We get theses macromolecules by eating them, and in the context of nutrition are sometimes called [[nutrients|macronutrients]]. ___