How do enzymes facilitate chemical digestion?

Enzymes facilitate chemical digestion by speeding up the breakdown of complex molecules into simpler ones for absorption.

Enzymes are biological catalysts that play a crucial role in chemical digestion. They work by lowering the activation energy required for a chemical reaction to occur, thus speeding up the process. In the context of digestion, enzymes break down complex food molecules such as proteins, carbohydrates, and fats into simpler molecules like amino acids, sugars, and fatty acids. This process is essential as it allows these simpler molecules to be easily absorbed by the body.

The process begins in the mouth, where the enzyme amylase in saliva starts the breakdown of carbohydrates into sugars. As the food travels down the oesophagus and into the stomach, the enzyme pepsin begins to break down proteins into smaller peptides. The food then moves into the small intestine, where several enzymes, including lipase, maltase, sucrase, and lactase, continue the digestion process. Lipase breaks down fats into fatty acids and glycerol, while maltase, sucrase, and lactase break down different types of sugars.

Each enzyme is specific to a particular substrate, meaning it can only catalyse a reaction involving a specific molecule. This specificity is due to the unique shape of the enzyme's active site, which only fits the particular molecule it is meant to act upon. This is known as the 'lock and key' model of enzyme action.

In summary, enzymes are vital for chemical digestion as they speed up the breakdown of complex food molecules into simpler ones. This process is essential for the absorption and utilisation of nutrients by the body. Without enzymes, digestion would be a slow and inefficient process.