mass transport

Question 1

what is digestion?

Answer 1

the breakdown of large insoluble molecules into smaller more soluble molecules

Question 2

What does the enzyme amylase do?

Answer 2

catalyses the breakdown of starch into molecules into maltose

Question 3

where do amylase and other carbohydrases get produced?

Answer 3

• salivary glands
• pancreas
• small intestine

Question 4

what are membrane bound disaccharides?

Answer 4

enzymes that are attached to the cell membrane of epithelial cells lining the ileum

Question 5

what do membrane bound disaccharides do?

Answer 5

help breakdown disaccharides into monosaccharides via the hydrolysis of glycosidic bonds.

Question 6

what is sucrose hydrolysed into and what enzyme catalyses this reaction?

Answer 6

• sucrose = glucose + fructose

- sucrase

Question 7

what is maltose hydrolysed into and what enzyme catalyses this reaction?

Answer 7

• maltose = glucose + glucose

- maltase

Question 8

what is lactose hydrolysed into and what enzyme catalyses this reaction?

Answer 8

• lactose = glucose + galactose

- lactase

Question 9

what do lipids get hydrolysed into?

Answer 9

fatty acids and glycerol

Question 10

where are lipases secreted?

Answer 10

• pancreas

- small intestine

Question 11

where are by salts produced and what do they do?

Answer 11

• produced in the liver

- they emulsify lipids into smaller droplets

Question 12

are bile salts enzymes?

Answer 12

no but they increase the surface area as they produce smaller droplets for the lipases to work on.

Question 13

what happens when monoglycerides and fatty acids stick together with bile salts?

Answer 13

they form micelles

Question 14

what do micelles do?

Answer 14

they help the products of lipid digestion to be absorbed

Question 15

what are micelles the product of?

Answer 15

monoglycerides + fatty acid + bile salts

Question 16

what is the name of the enzymes that catalyse the breakdown of proteins into amino acids?

Answer 16

proteases / peptidases

Question 17

what do endopeptidases do?

Answer 17

hydrolyse peptide bonds within a protein

Question 18

what do exopeptidases do?

Answer 18

hydrolyse peptide bonds at the end of proteins (remove single amino acids)

Question 19

what do dipeptidases do?

Answer 19

work specifically on dipeptides

Question 20

where are dipeptides located?

Answer 20

they are often located in the cell surface membrane of epithelial cells and are membrane bound

Question 21

what happens to the products of digestion?

Answer 21

the products of digestion are absorbed across the ileum epithelium into the bloodstream

Question 22

how is glucose absorbed into the bloodstream?

Answer 22

by active transport with sodium ions via a co-transporter protein

Question 23

how is galactose absorbed into the bloodstream?

Answer 23

by active transport with sodium ions via a co-transporter protein

Question 24

how is fructose absorbed into the bloodstream?

Answer 24

by facilitated diffusion through a carrier protein

Question 25

how do micelles allow the products of lipid digestion to be absorbed?

Answer 25

• they help to move monoglycerides and fatty acids towards the epithelium
• micelles constantly break and reform , they can ‘release’ monoglycerides ad fatty acids to be absorbed.
• they are lipid soluble and so diffuse directly across the epithelium membrane.

Question 26

how are amino acids absorbed into the bloodstream?

Answer 26

• by active transport
• via sodium-dependant transporter proteins
• sodium carries amino acids with it