Describe the roles of enzymes in digestion

Enzymes are catalysts which will speed up chemical reactions without getting used up themselves. They also have particular active sites, whose shape is specific for one specific substrate; therefore, enzymes are highly specific molecules.

Enzymes are used in digestion to break down large, insoluble molecules into smaller, soluble matter that can be dissolved. The first digestive enzyme is found in the saliva, and it is amylase. This is a type of carbohydrate, and its substrate is starch. The starch gets broken down into glucose monomers.

Another digestive enzyme is lipase, which is found in the pancreas. It's substrate is fats, which will get broken down to glycerol and fatty acids.

Pepsin is a type of protease enzyme which is found in the stomach. This is one of the main digestive enzymes and it will bind to proteins and break them into amino acids.

Once the food has been made into small, water-soluble molecules, it will be absorbed into the watery blood plasma, so that it can be utilised by other cells.