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  • Proteins are one of four main classes of biomolecules in living organisms. The others are lipids, which form our membranes, nucleic acids (DNA and RNA), which carry and carry out our instructions, and carbohydrates, which not only give us energy but are also sometimes involved in signalling processes and other cellular processes. Proteins are the most diverse of these four biomolecules.

    Enzymes are proteins that catalyse chemical reactions – they are biocatalysts. Catalysts make chemical reactions happen much more quickly than is possible spontaneously. Biocatalysts naturally carry out their action in living organisms. Most biochemical reactions, if left to their own devices, will take millions of years to occur but can occur within cells in milliseconds due to the action of enzymes.

    There are thousands of enzymes within each living organism and each has a specific role – controlling essential biological and biochemical reactions by working with specific substrates to create specific products.

    Some common enzymes found in animals are used in the digestion system. Amylase is found in saliva and helps the breakdown of starches into sugars. Trypsin is found in the small intestine and breaks down protein into amino acids. Lipases are a group of enzymes that help digest fat in the gut.

    Nature of science

    The animation within this article is a model created to help visualise the action of enzymes. Scientists often use models to help build and communicate their understandings about the world.

      Published 8 February 2022 Referencing Hub articles
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