Breaking down large carbohydrates
Digestion uses hydrolysis to convert large biological molecules into smaller molecules that are able to cross cell membranes.
Digestive enzymes catalyse these reactions extracellularly, so digestion occurs outside body cells before the products are absorbed.
1
Large carbohydrate
Starch is a large carbohydrate that must first be broken into smaller sugar molecules.
2
Hydrolysis
Carbohydrase enzymes catalyse hydrolysis reactions that progressively digest the carbohydrate.
3
Smaller products
The process ultimately produces small sugars such as glucose that can be absorbed.
For starch, digestion occurs in stages: amylase first produces maltose, after which a membrane-bound disaccharidase completes its digestion to glucose.