Digestion and absorption

During digestion, large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes.

Digestion in mammals of:

• carbohydrates by amylases and membrane-bound disaccharidases

• lipids by lipase, including the action of bile salts

• proteins by endopeptidases, exopeptidases and membrane-bound dipeptidases.

Mechanisms for the absorption of the products of digestion by cells lining the ileum of mammals, to include:

• co-transport mechanisms for the absorption of amino acids and of monosaccharides

• the role of micelles in the absorption of lipids.

PS 1.1

Students could:

• design and carry out investigations into the effect of a pH or bile salts on the rate of reaction catalysed by a digestive enzyme

• use Visking tubing models to investigate the absorption of the products of digestion.