Organisms Exchange Substances with their Environment: Digestion & Absorption - Digestion

Question 1

What happens during digestion?

Answer 1

• During digestion large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes

Question 2

Which enzymes are involved in carbohydrate digestion? Where are they found?

Answer 2

• Amylase

• Produced by salivary glands and pancreas
• Released in mouth and small intestine

• Maltase, sucrase, lactase
- Found attached to cell membrane of epithelial cells lining the small intestine (ileum)

Question 3

What are membrane-bound disaccharidases?

Answer 3

• Enzymes that are attached to cell membranes of epithelial cells lining the ileum
• They help hydrolyse disaccharides into monosaccharides
• Maltase, sucrase, lactase

Question 4

List some membrane-bound disaccharidases and list which disaccharides they help hydrolyse

Answer 4

• Sucrase

• Disaccharide: sucrose
• Monosaccharides: glucose and fructose

• Maltase

• Disaccharide: maltose
• Monosaccharides: a-glucose and a-glucose

• Lactase

• Disaccharide: lactose
• Monosaccharides: glucose and galactose

Question 5

Which bonds do carbohydrases hydrolyse?

Answer 5

• Glycosidic bonds

Question 6

What types of molecules do lipase enzymes help hydrolyse?

Answer 6

• Lipase enzymes catalyse the hydrolysis of lipids into monoglycerides and fatty acids
• This involves the hydrolysis of ester bonds

Question 7

Where are lipase found and made?

Answer 7

• Mainly made in pancreas

- Secreted into small intestine

Question 8

What types of molecules do peptidases enzymes help hydrolyse?

Answer 8

• Peptidases catalyse the hydrolysis of proteins into amino acids
• Involves hydrolysing peptide bonds

Question 9

What are the three types of peptidases?

Answer 9

• Endopeptidases
- Hydrolyse peptide bonds within a protein

• Exopeptidases

• Hydrolyse peptide bonds at the ends of polypeptides
• They remove terminal amino acids from proteins

• Dipeptidases

• Type of exopeptidase
• Work specifically on dipeptides
• Separate two amino acids by hydrolysing the peptide bond between them
• Often located on cell-surface membrane of epithelial cells in small intestine