Digestion and absorption – AQA A Level Biology Summary Notes
Digestion = large biological molecules are hydrolysed into smaller molecules that can be absorbed
from ileum, across cell membranes, into the blood
Digestion of mammals of: carbohydrates by amylases and membrane-bound disaccharides
Starch — Maltose — Glucose
1. Polymer of alpha glucose
2. Digestion of starch starts in mouth by mechanical digestion eg chewing and then small
intestine
3. Amylase produced in salivary glands and secreted to the mouth
4. Amylase, a carbohydrase, catalyses the hydrolysis of glycosidic bonds in amylose to form the
disaccharide maltose.
5. Acidity of stomach denatures amylase, no further hydrolysis
6. Small intestine has alkaline conditions so food is mixed with pancreatic juices eg pancreatic
amylase
7. So pH is neutral for optimum conditions for amylase
Digestion = large biological molecules are hydrolysed into smaller molecules that can be absorbed
from ileum, across cell membranes, into the blood
Digestion of mammals of: carbohydrates by amylases and membrane-bound disaccharides
Starch — Maltose — Glucose
1. Polymer of alpha glucose
2. Digestion of starch starts in mouth by mechanical digestion eg chewing and then small
intestine
3. Amylase produced in salivary glands and secreted to the mouth
4. Amylase, a carbohydrase, catalyses the hydrolysis of glycosidic bonds in amylose to form the
disaccharide maltose.
5. Acidity of stomach denatures amylase, no further hydrolysis
6. Small intestine has alkaline conditions so food is mixed with pancreatic juices eg pancreatic
amylase
7. So pH is neutral for optimum conditions for amylase
