Enzymes + Digestion 2 Flashcards
Why does carbohydrate digestion require more than one enzyme?
Large molecules are hydrolysed in stages, with different enzymes acting on different sections
Why is the sequence of enzyme action important in digestion?
Each enzyme prepares the substrate for the next enzyme, ensuring complete digestion into monomers
Where is amylase produced, and what does it do?
It is produced in the mouth by the salivary glands, and by the pancreas
Amylase hydrolyses starch into maltose by breaking glycosidic bonds
Where is maltase produced?
Maltase is produced by the lining of the ileum
What happens to maltose after amylase action?
Maltose is hydrolysed into alpha glucose by maltase, a disaccharidase enzyme
What enzyme is present in saliva, and what does it do?
Salivary amylase is present in saliva, which hydrolyses starch into maltose
Why does saliva contain mineral salts?
They help maintain a neutral pH, which is the optimum pH for salivary amylase
What happens to amylase in the stomach?
The stomach’s acidic conditions denature amylase, stopping starch hydrolysis
What enzyme continues starch digsstion in the small intestine?
Pancreatic amylase, found in pancreatic juice
Why are alkaline salts produced in the small intestine?
To maintain a neutral pH, allowing pancreatic amylase to function
What enzyme hydrolyses maltose, and where is it found?
Maltase, which is membrane - bound in the epithelial cells of the ileum
What is the final product of starch digestion?
Alpha glucose, which is absorbed into the bloodstream
What is the process of carbohydrate digestion? (7 steps)
1. Mouth - maltose - maltase
2. Amylase - hydrolysis - maltose
3. Swallow - denature - hydrolysis
4. Food - small intestine - pancreas
5. Pancreatic juice - hydrolysis - starch
6. Muscles - push - ileum
7. Maltase - hydrolysis - alpha glucose
1/ Salivary glands secrete amylase into the mouth, starting the hydrolysis of carbohydrate polysaccharide (starch) into the disaccharide (maltose)
2/ Amylase hydrolyses the glycosidic bonds in starch into the disaccharide maltose
3/ The food is then swallowed into the stomach, where the acidic conditions denature the amylase and stop the further hydrolysis of starch
4/After some time, the food passes into the small intestine, where it mixes with the pancreatic juice from the pancreas
5/ Pancreatic juice containing pancreatic amylase continues the hydrolysis of any remaining starch to maltose
6/ Muscles in the intestinal wall push the food along the ileum
7/ The epithelial lining produces the disaccharide maltase which hydrolyses the maltose from starch breakdown into alpha glucose
What are the two other common disaccharides in the human diet, apart from maltose?
Sucrose and lactose
What enzyme hydrolyses sucrose, and what are the products?
Sucrase hydrolyses sucrose into glucose and fructose
What enzyme hydrolyses lactose, and what are the products?
Lactase hydrolyses lactose into glucose and galactose
Where are sucrase and lactase found in the digestive system?
They are membrane - bound disaccharides found in the epithelial cells of the ileum
