But most major nutrients in food are large molecules which cannot pass through the cell membranes.
They must be broken down into molecules that are small enough to pass through the cell membranes.
This process is called digestion .
Digestion is the breaking down of large, complex food molecules into small, simpler molecules.
Our body is able to carry out digestion by producing complex proteins called enzymes .
The enzymes involved in digestion are called digestive enzymes .
Nutrients like starch, proteins and fats, are large, complex molecules. They cannot pass through the cell membrane. Nutrients like glucose and amino acids, are small, soluble molecules. They can pass through the cell membrane.