Digestion
1.what is digestion?
● The process in which large molecules are hydrolysed by enzymes into smaller
molecules that can be absorbed across cell membranes
Lipid digestion
2.what is the role of lipase?
● Hydrolyse the ester bond found in triglycerides to form monoglycerides + fatty acids
3.where is lipase present?
● Small intestine
4.why is creating an emulsion an advantage to digestion?
● Bec many small droplets of lipids are created which provides a large SA to enable the
faster hydrolysis action by lipase
● Providing large SA means more enzymes can attach so more E-S complexes so faster
hydrolysis
5.what is the role of bile salts?
● Produced in liver
● Emulsify lipids to form tiny droplets (micelles), which increases the SA for lipase to act
on—-> process= emulsification
6.describe the chemical digestion of lipids?
● Lipase hydrolyses lipids into glycerol + fatty acids (some monoglycerides)
7.what are micelles?
● Water soluble vesicles formed from the fatty acids, glycerol, monoglycerides + bile salts
8.what do micelles do?
● Deliver the fatty acids, glycerol + monoglycerides to epithelial cells of illeum for
absorption
5.describe protein digestion
● It is the hydrolysis of peptide bonds
● Endopeptidases- break polypeptides into smaller peptide chains / hydrolyse peptide
bonds between AA in middle of polypeptide
● exopeptidases - remove terminal AA / hydrolyse peptide bonds on terminal AA at end
of polypeptide
● Dipeptidases- hydrolyse dipeptides into AA / hydrolyse the peptide bond between 2 AA
of a dipeptide
, 6.where is amylase produced?
● Salivary glands or pancreas
● Pancreas secretes amylase into small intestine
7.what is the role of amylase?
● Hydrolyse starch to maltose
8.where are membrane- bound disaccharides found?
● Membrane of small intestine disaccharides = sucrose, lactose, maltose
9. What is the role of membrane- bound disaccharides?
● Hydrolyse disaccharides e.g. maltose to monosaccharides, e.g. glucose
10. What are the adaptations of the ileum wall?
● Covered in villi + epithelial cells have even smaller microvilli- increases SA for
absorption
● Thin walls- provide short diffusion distance
● Network of capillaries- maintain conc gradient
11. How are the products of starch digestion absorbed?
● Glucose moves in with Na+ ion
● Through carrier protein
● Sodium removed from epithelial cell by active transport into the blood
● Maintaining a low concentration of sodium in epithelial cell
● Glucose moves into blood by facilitated diffusion
12.how are lipids absorbed after they are digested?
● Micelles contain bile salt, fatty acids + monoglycerides
● Micelles make fatty acids more water soluble
● Micelles bring fatty acids to cell membrane/ epithelial cells of illeum
● Fatty acids absorbed by diffusion
● Maintain higher concentration of fatty acids to cells lining ileum
13.describe the mechanism for the absorption of AA in the illeum?
● Facilitated diffusion of AA into cell when higher conc in lumen
● Co- transport
● Na+ actively transported from cell to blood/ capillary
● Creating a sodium ion conc/ diffusion gradient
● Facilitated diffusion of AA into blood/ capillary
1.what is digestion?
● The process in which large molecules are hydrolysed by enzymes into smaller
molecules that can be absorbed across cell membranes
Lipid digestion
2.what is the role of lipase?
● Hydrolyse the ester bond found in triglycerides to form monoglycerides + fatty acids
3.where is lipase present?
● Small intestine
4.why is creating an emulsion an advantage to digestion?
● Bec many small droplets of lipids are created which provides a large SA to enable the
faster hydrolysis action by lipase
● Providing large SA means more enzymes can attach so more E-S complexes so faster
hydrolysis
5.what is the role of bile salts?
● Produced in liver
● Emulsify lipids to form tiny droplets (micelles), which increases the SA for lipase to act
on—-> process= emulsification
6.describe the chemical digestion of lipids?
● Lipase hydrolyses lipids into glycerol + fatty acids (some monoglycerides)
7.what are micelles?
● Water soluble vesicles formed from the fatty acids, glycerol, monoglycerides + bile salts
8.what do micelles do?
● Deliver the fatty acids, glycerol + monoglycerides to epithelial cells of illeum for
absorption
5.describe protein digestion
● It is the hydrolysis of peptide bonds
● Endopeptidases- break polypeptides into smaller peptide chains / hydrolyse peptide
bonds between AA in middle of polypeptide
● exopeptidases - remove terminal AA / hydrolyse peptide bonds on terminal AA at end
of polypeptide
● Dipeptidases- hydrolyse dipeptides into AA / hydrolyse the peptide bond between 2 AA
of a dipeptide
, 6.where is amylase produced?
● Salivary glands or pancreas
● Pancreas secretes amylase into small intestine
7.what is the role of amylase?
● Hydrolyse starch to maltose
8.where are membrane- bound disaccharides found?
● Membrane of small intestine disaccharides = sucrose, lactose, maltose
9. What is the role of membrane- bound disaccharides?
● Hydrolyse disaccharides e.g. maltose to monosaccharides, e.g. glucose
10. What are the adaptations of the ileum wall?
● Covered in villi + epithelial cells have even smaller microvilli- increases SA for
absorption
● Thin walls- provide short diffusion distance
● Network of capillaries- maintain conc gradient
11. How are the products of starch digestion absorbed?
● Glucose moves in with Na+ ion
● Through carrier protein
● Sodium removed from epithelial cell by active transport into the blood
● Maintaining a low concentration of sodium in epithelial cell
● Glucose moves into blood by facilitated diffusion
12.how are lipids absorbed after they are digested?
● Micelles contain bile salt, fatty acids + monoglycerides
● Micelles make fatty acids more water soluble
● Micelles bring fatty acids to cell membrane/ epithelial cells of illeum
● Fatty acids absorbed by diffusion
● Maintain higher concentration of fatty acids to cells lining ileum
13.describe the mechanism for the absorption of AA in the illeum?
● Facilitated diffusion of AA into cell when higher conc in lumen
● Co- transport
● Na+ actively transported from cell to blood/ capillary
● Creating a sodium ion conc/ diffusion gradient
● Facilitated diffusion of AA into blood/ capillary
