Enzymes

Definition

Biological catalysts, mostly proteins, that speed up the chemical reactions inside living organisms without being used up themselves.

Key points

• Each enzyme is highly specific and acts on a particular substance (substrate), often described by a "lock and key" fit between enzyme and substrate.
• Enzymes work best within a narrow range of temperature and pH; outside this range they lose shape (denature) and stop working, which is why high fever or extreme acidity disrupts body functions.
• Digestive enzymes include amylase (breaks starch, in saliva and pancreas), pepsin (breaks proteins, in the acidic stomach), and lipase (breaks fats).
• Enzymes drive respiration, digestion, photosynthesis, and DNA copying; many are made of protein, though some RNA molecules also act as catalysts.
• Industrial and household uses include enzymes in detergents, in cheese and bread making, and in producing biofuels.

Why it matters for CAPF

Enzymes as biological catalysts, their specificity, the effect of temperature and pH, and the major digestive enzymes are recurring biology and chemistry facts.

Common confusion

Enzymes are catalysts, so they are not consumed and do not change the products, only the speed; they are not reactants. Pepsin works in the acidic stomach, while amylase works in near-neutral conditions, so the same enzyme does not act everywhere. Most but not all enzymes are proteins.

Related concepts

concept catalysts, concept photosynthesis, concept acids bases and salts

Parent note

biology cell and classification