digestion and absorption

Question 1

define digestion

Answer 1

hydrolysis of large, insoluble molecules into smaller molecules that can be absorbed across cell membranes

Question 2

which enzymes are involved in carbohydrate digestion and where are they

Answer 2

• amylase in mouth
• maltase, sucrase and lactase in membrane of ileum

Question 3

where are lipids digested

Answer 3

ileum

Question 4

what needs to happen before lipids can be digested

Answer 4

emulsification
- emulsified by bile salts produced by liver
- breaks large fat molecules into smaller, soluble molecules called micelles, increasing surface area

Question 5

how are lipids digested

Answer 5

lipase hydrolyses the ester bond between the monoglycerides and fatty acids

Question 6

which enzymes are involved in protein digestion? what is their role?

Answer 6

endopeptidases - bonds in middle
exopeptidases - bonds on end
dipeptidases - break dipeptides into amino acids

Question 7

how are certain molecules absorbed into the ileum despite negative concentration gradient

Answer 7

through co-transport

Question 8

which molecules require co-transport

Answer 8

amino acids and monosaccharides

Question 9

explain how sodium ions are involved in co-transport

Answer 9

Na+ actively transported out of cell into lumen, creating a diffusion gradient
nutrients are then taken up into the cells along with Na+ ions

Question 10

why do fatty acids and monoglycerides not require co-transport

Answer 10

molecules are nonpolar, meaning they can easily diffuse across the membrane of the epithelial cells