exchange and transport (digestion)

Question 1

what is digestion?

Answer 1

when large insoluble molecules are hydrolysed into smaller molecules, which can be absorbed across cell membranes

Question 2

what are carbohydrates broken down by?

Answer 2

amylase and membrane bound disaccharides

Question 3

what does amylase catalyse the conversion of?

Answer 3

starch into maltose

Question 4

how does starch get broken down?

Answer 4

hydrolysis of the glycosidic bonds in starch

Question 5

where is amylase produced?

Answer 5

the salivary glands and pancreas

Question 6

what are membrane bound disaccharides?

Answer 6

enzymes attached to cell membranes of epithelial cells lining the ileum- break down disaccharides into monosaccharides

Question 7

what is maltose broken down into?

Answer 7

2 alpha glucose

Question 8

what is sucrose broken down into?

Answer 8

glucose and fructose

Question 9

what is lactose broken down into?

Answer 9

glucose and galactose

Question 10

how is starch digested?

Answer 10

saliva enters the mouth from the salivary glands
hydrolyses starch in food to maltose
denatured in the stomach
enters the stomach- pancreatic juice hydrolyses starch to maltose
ileum produces maltase- hydrolyses starch to alpha glucose

Question 11

what enzyme is a lipid broken down by?

Answer 11

lipase

Question 12

what does lipase break a lipid down into?

Answer 12

monoglycerides and fatty acids

Question 13

how are lipids broken down into monoglycerides and fatty acids?

Answer 13

hydrolysis of the ester bond

Question 14

where are lipases made?

Answer 14

pancreas

Question 15

where do lipases work?

Answer 15

small intestine

Question 16

where are bile salts produced?

Answer 16

in the liver

Question 17

what do bile salts do?

Answer 17

emulsify lipids- break down lipids into smaller droplets which increase the surface area for digestion

Question 18

what is a micelle?

Answer 18

monolglycerides and fatty acids combined with bile salts

Question 19

what is physical lipid digestion?

Answer 19

emulsification and micelle formation

Question 20

what is chemical lipid digestion?

Answer 20

lipase hydrolyses lipids into fatty acids and glycerol

Question 21

how are lipids digested?

Answer 21

micelles meet epithelial cells
fatty acids and monoglycerides are non polar
these diffuse across the membrane
and are modified to form triglycerides in the endoplasmic reticulum and golgi body
form chylomicrons
leave by exocytosis

Question 22

what enzymes break down proteins?

Answer 22

proteases (endopeptidases, exopeptidases, dipeptidases)

Question 23

what does an endopeptidase do?

Answer 23

hydrolyses peptide bonds between amino acids in the middle of polymer chain

Question 24

what does an exopeptidase do?

Answer 24

hydrolyses peptide bonds between amino acids at the end of a polymer chain

Question 25

what does a dipeptidase do?

Answer 25

hydrolyses peptide bonds between 2 amino acids

Question 26

where does protein digestion start and end?

Answer 26

starts in the stomach

completed in the ileum

Question 27

where are dipeptidases usually located?

Answer 27

cell surface membrane of epithelial cells in the small intestine

Question 28

how are glucose and galactose absored into the bloodstream?

Answer 28

active transport with sodium ions via a co transporter protein

Question 29

how is frutose absorbed into the bloodstream?

Answer 29

via faciliated diffusion through a transporter protein

Question 30

how are monoglycerides and fatty acids absorbed into the bloodstream?

Answer 30

micelles release monoglycerides and fatty acids

these are lipid soluble so can diffuse directly across the epithelial cell membrane

Question 31

how are amino acids absorbed into the bloodstream?

Answer 31

via co transport
sodium ions are actively transported out of the epithelial cells into the blood
creates a sodium ion concentration gradient
sodium ions can diffuse through sodium-dependent transporter proteins, carrying the amino acids with them