3.3.3 Digestion and Absorption Flashcards
Amylase hydrolyses starch into…
Maltose
What is digestion
The process where large insoluble molecules are hydrolysed into smaller molecules that can be absorbed across the cell membrane
2 types of enzyme involved in digestion of carbohydrates
Amylase
Membrane bound disaccharidases
3 types of enzyme involved in the digestion of proteins
Endopeptidases
Exopeptidases
Dipeptidases
Which bonds do endopeptidases hydrolyse
The peptide bonds between the amino acids in the middle of the polypeptide chain
Which bonds do exopeptidases hydrolyse
Peptide bonds between amino acids at the ends of the polypeptide chain
Which bonds do membrane-bound dipeptidases hydrolyse
The peptide bond between 2 amino acids in a dipeptide
What 2 key things are involved in the digestion of lipids
Lipase
Bile salts
Lipase hydrolyses triglycerides into what 3 products
Fatty acids, glycerol, monoglycerides
Bile salts…lipids to produce an emulsion of lipid droplets and provide a large surface area for lipase enzymes to act on.
Emulsify
The emulsification of triglycerides (lipids) to an emulsion of lipid droplets is a form of what type of digestion
Physical
What are the 2 types of digestion
Chemical and physical
What 4 things does a micelle contain
Fatty acids, glycerol, monoglycerides and bile salts
Once fatty acids, glycerol and monoglycerides have been produced from the hydrolysis of triglycerides how are they transported to the ileum to be absorbed
By micelles
(Tiny structures made of fatty acids, glycerol, monoglycerides and bile salts)
What happens when the micelles (containing fatty acids, glycerol, monoglycerides and bile salts) reach the micro villi of the epithelial cells in the ileum
The micelles release the fatty acids, glycerol and monoglycerides which cross the phospholipid bilayer by simple diffusion to enter the epithelial cell
Monosaccharides and amino acids are absorbed (cross the cell membrane and enter the epithelial cells in the ileum) by…
Co transport
True or false, Co transport requires ATP
True
After lipid digestion, what happens once the fatty acids, glycerol and monoglycerides have entered the epithelial cells in the ileum by simple diffusion
At the smooth endoplasmic reticulum the fatty acids, glycerol and monoglycerides are synthesised back into triglycerides
The triglycerides are transported in vesicles to the Golgi apparatus
At the Golgi apparatus the triglycerides are modified and combined with proteins to form chylomicrons
The chylomicrons are then packaged into vesicles which are released from the cell by exocytosis
