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What are enzymes?

Enzymes are biological catalysts.

A catalyst is a molecule that increases the rate (speed) of a reaction. Enzymes act as catalysts for chemical reactions in the cell.

It is unlikely glucose molecules will spontaneously form a starch molecule. The cell uses an enzyme (starch synthase) to produce starch quickly.

Like all proteins, enzymes are formed from chains of amino acids. In enzymes, the chains form a globular structure (spherical):

The reacting molecules in enzyme-driven reactions are called substrates.
The reacting molecules in enzyme-driven reactions are called substrates.

There are several important features of enzymes:

  • Highly specific: Each enzyme only acts on a single type of reaction.
  • Unchanged: Enzymes are not altered by their reactions.
  • Reusable: Enzymes can be used multiple times.