Biosynthesis is a phenomenon wherein chemical compounds are produced from simpler reagents. Biosynthesis, unlike chemosynthesis, takes place within living organisms and is generally catalyzed by enzymes. The process is a vital part of metabolism.

The prerequisites for biosynthesis are:

• Precursor substances
• Energy (usually in the form of ATP).

Often required components include:

• Catalysts, usually enzymes
• Reduction equivalents (in the form of NADH, NADPH, and others).

Important and commonly-known products of biosynthesis include proteins, vitamins, and antibiotics, but all components of living beings are a result of this process. In the near future, it may be possible, with the help of biotechnology, to harness this process for the production of biodegradable plastics.