3.3 Digestion & Absorption Flashcards
(16 cards)
Define digestion
The hydrolysis of large, insoluble molecules into smaller molecules that can be absorbed across cell membranes.
Which enzymes are involved in carbohydrate digestion and where are they found?
Amylase in mouth; Maltase, sucrase, lactase in membrane of small intestine.
Substrates and products of amylase
Amylase → starch into smaller polysaccharides.
Substrates and products of maltase
Maltase → maltose into 2 x glucose.
Substrates and products of sucrase
Sucrase → sucrose into glucose and fructose.
Substrates and products of lactase
Lactase → lactose into glucose and galactose.
Location of lipid digestion
The small intestine.
Requirement before lipid digestion
They must be emulsified by bile salts produced by the liver.
Process of lipid digestion
Lipase hydrolyses the ester bond between the monoglycerides and fatty acids.
What are endopeptidases?
Enzymes that break between specific amino acids in the middle of a polypeptide.
What are exopeptidases?
Enzymes that break between specific amino acids at the end of a polypeptide.
What are dipeptidases?
Enzymes that break dipeptides into amino acids.
How are certain molecules absorbed into the ileum despite negative concentration gradient
Through co-transport.
What molecules require co-transport?
Amino acids and monosaccharides.
Role of sodium ions in co-transport
Sodium ions (Na+) are actively transported out of the cell into the lumen, creating a diffusion gradient.
Absorption of fatty acids and monoglycerides
The molecules are nonpolar, meaning they can easily diffuse across the membrane of the epithelial cells.
