💙 3.3.3 Digestion

Question 1

What is digestion?

Answer 1

Digestion is the breaking down of large insoluble molecules into smaller, soluble ones for absorption, into the blood. It involves the hydrolysis of bonds.

Question 3

What are the two enzymes involved in protein digestion?

Answer 3

Endopeptidases and exopeptidase

Question 4

What do Endopeptidases do during protein digestion?

Answer 4

They break down large polypeptide chains by hydrolysing peptide bonds in the middle of a polypeptide so that they can produce smaller peptides – for increased surface area for exopeptidases to work on.

Question 5

What do exopeptidases do ?

Answer 5

They hydrolyse peptide bonds near the end of polypeptides producing dipeptides.

Question 6

The the combined action of Exopeptidases and Endopeptidases makes digestion …

Answer 6

Faster

Question 7

What are the steps of protein digestion?

Answer 7

1) protein digestion begins in the stomach and is carried out by Endopeptidases.
2) the protein is further digested by more Endopeptidases along with Exopeptidases in the small intestine using sections from the pancreas
3) Final digestion occurs in the CMECLI
- these dipeptidase enzymes are embedded in the cell membrane of the epithelial cells lining the ileum and result in the release of amino acids. These monomers can then be absorbed.

Question 8

Describe the process of digestion of carbohydrates

Answer 8

1) carbohydrates have their glycosidic bonds hydrolysed during digestion
2) starch is hydrolysed to maltose – initially in the mouth by the salivary amylase and laterly in the small intestine by pancreatic amylase
3) maltose (a disaccharide (along with other disaccharides) is then hydrolysed into glucose by disaccharides (maltase) in the CMECLI (cell membrane of the epithelial cells lining the ileum).

Question 9

What is the process of digestion of lipids?

Answer 9

1) Emulsification (breaking down large droplets into smaller droplets) of lipid by bile salts/bile from the liver
2) hydrolysis of Ester bonds - this increases the surface area for lipase to work on making it a faster process
3) lipase is from the pancreas
4) digestion of lipids in the small intestine
5) the lipids are digested into fatty acids and monoglycerides