Biology: Digestion and Absorption of Proteins

Question 1

What enzymes hydrolyse proteins?

Answer 1

protease and peptidases

Question 2

Where does protein digestion occur?

Answer 2

in stomach and small intestine

Question 3

What happens in protein digestion in the stomach?

Answer 3

-HCL denatures proteins, unfolding 3D structure to reveal polypeptide chain
-pepsin hydrolyses chain into shorter polypeptide chains

Question 4

What happens in protein digestion in the small intestine?

Answer 4

-trypsin/protease/chymotrypsin hydrolyse proteins into tripeptides, dipeptides and amino acids
-enterocytes/tripeptides/dipeptides further hydrolysed into amino acids
-amino acids absorbed by bloodstream

Question 5

What are the three types of protease?

Answer 5

-endopeptidase -exopeptidase -dipeptidase

Question 6

What do endopeptidases work on?

Answer 6

hydrolyse peptide bonds on large chain to form smaller chain and create terminal ends

Question 7

What do exopeptidases work on?

Answer 7

hydrolyse terminal peptide bonds to remove individual amino acids and form smaller chains

Question 8

What do dipeptidases work on?

Answer 8

hydrolyse peptide bonds in dipeptides to form two single amino acids

Question 9

What mechanism absorbs amino acids?

Answer 9

active co-transport with sodium ions

Question 10

How are amino acids absorbed by the small intestine?

Answer 10

-sodium ions actively transported into ileum from epithelial
-active transport of sodium ions out of cell into blood via sodium-potassium pump
-sodium ions and amino acids diffuse in facilitated diffusion using carrier proteins
-movement down concentration gradient is required