·
Macromolecules
will be broken down (digested) into smaller soluble food molecules by ENZYMES.
Enzymes are
biological catalysts. They speed up the chemical digestion of food. Each enzyme is specific to the food substance it works on. In other words, only a particular type of enzyme will act on carbohydrates. This enzyme will NOT act on any other substance.
Enzymes work by the
LOCK & KEY THEORY.
The
ACTIVE SITE of the enzyme is the key to this process. The shape of the active site is what gives the enzyme its specificity.
The enzyme is the key and the substance it acts on (called the
substrate) is the lock.
For example, in the mouth, the carbohydrate macromolecule, starch is digested by the carbohydrase enzyme
salivary amylase. The product of this chemical digestion is the smaller, soluble carbohydrate glucose.
The shape of the enzyme's active site can be easily damaged by high temperatures and the wrong pH. We say the active site becomes
denatured.
