Digestion & 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? Where are they found?

Answer 2

• Amylase in mouth
• Maltase, sucrase, lactase in membrane of small intestine

Question 3

What are the substrates & products of carbohydrate digestive enzymes?

Answer 3

• Amylase -> starch into smaller polysaccharides
• Maltase -> maltose into 2x glucose
• Sucrase -> sucrose into glucose & fructose
• Lactase -> lactose into glucose & galactose

Question 4

What needs to happen before lipids can be digested?

Answer 4

Must be emulsified by bile salts produced y liver. This breaks down large fat molecules into smaller, soluble molecules called micelles, increasing surface area

Question 5

How are lipids digested?

Answer 5

Lipase hydrolyses ester bond between monoglycerides and fatty acids

Question 6

Which enzymes are involved in protein digestion? What is their role?

Answer 6

• Endopeptidases = break between specific amino acids in middle of a polypeptide
• Exopeptidases = break between specific amino acids at end of a polypeptide
• Dipeptidases = break dipeptidases into amino acids

Question 7

Which molecules require co-transport?

Answer 7

Amino acids and monosaccharides

Question 8

Explain how sodium ions are involved in co-transport

Answer 8

Sodium ions (Na+) are actively transported out of cell into lumen, creating diffusion gradient. Nutrients are then taken up into cells along with Na+ ions

Question 9

Why do fatty acids & monosaccharides not require co-transport?

Answer 9

Molecules are non-polar, meaning they can easily diffuse across membrane of epithelial cells