Digestion Flashcards
On a basic level, what happens during digestion?
Larger molecules (carbohydrates) are broken down by hydrolysis into disaccharides, then monosaccharides.
What is physical digestion?
When large food pieces are broken down into smaller pieces by the teeth. This means the food can be ingested and provides a large SA for chemical digestion.
What are the three main types of digestive enzyme?
- carbohydrase
- lipase
- protease
Amylase is involve in carbohydrate digestion. Where is it produced?
In the mouth and pancreas
What does amylase do?
Amylase hydrolysed alternate glycosidic bonds of the starch molecule, to produce MALTOSE.
This maltose is, in time, hydrolysed into a-glucose (monosaccharide) by maltAse.
What are the monosaccharide products of maltose?
Glucose + glucose
What are the monosaccharide products of sucrose?
Glucose + fructose
What are the monosaccharide products of lactose?
Glucose + galactose
Maltase (involved in carbohydrate digestion) is a membrane-bound disaccharidase. What does this mean?
It’s an enzyme that attaches to the cell membranes of epithelial cells lining the ileum.
And helps to break down disaccharides (eg maltose) into monosaccharides (glucose). This involves the hydrolysis of glycosidic bonds.
Lipids are hydrolysed by ________.
Lipases.
Lipases are involved in lipid digestion. What do they involve?
They’re enzymes produced in the pancreas.
They hydrolyse the ester bond found in triglycerides to form fatty acids and monoglycerides.
Lipases hydrolyse triglycerides into fatty acids and monoglycerides. But what are monoglycerides?
A glycerol molecule with a single fatty acid molecule attached
How does emulsification help in lipid digestion?
Lipids (fats and oils) are split up into tiny droplets: micelles by bile salts, produced in the liver.
This increases the SA of lipids so that the action of lipases is sped up.
What are the three types of proteases (peptidases) involved in protein digestion?
- endopeptidase, exopeptidase, dipeptidase.
Outline how endopeptidases are involved in protein digestion.
Endopeptidases hydrolyse the peptide bonds between AAs.
Give two example of endopeptidases.
Trypsin.
Pepsin.
Outline how exopeptidases are involved in protein digestion.
Exopeptidases hydrolyse the peptide bonds on terminal amino acids.
In this way, they remove single AAs from proteins.
Outline how dipeptidases are involved in lipid digestion.
Dipeptidases hydrolyse the bond between the two AAs of a dipeptide.
What is the function of amylase in digestion?
Amylase (digestive enzyme) catalyse style conversion of starch (polysaccharide) into maltose (disaccharide). This involves the hydrolysis of the glycosidic bonds in starch.
Describe the role of bile salts in lipids digestion.
Bile salts (produced by liver) emulsify lipids, so they form smaller droplets aka micelles which increase SA.
How are the products of digestion absorbed?
Across the ileum epithelium into the bloodstream.
