digestion

Question 1

what is digestion

Answer 1

the process in which large, complex molecules are hydrolysed into smaller, soluble molecules that can be absorbed across cell membranes

Question 3

what are the two types of amylase and where are they found

Answer 3

salivary amylase - in mouth

pancreatic amylase - in small intestine

Question 4

what is maltase and what does it digest

Answer 4

membrane bound enzymes
hydrolyse disaccharides into monosaccharides

Question 5

what molecules are absorbed by co transport

Answer 5

glucose and amino acids

Question 6

what do amylases digest

Answer 6

starch into maltose by hydrolysing glycosidic bonds

Question 7

describe the mechanism of cotransport

Answer 7

1. sodium ions are actively transported out of epithelial cells into blood to provide concentration gradient
2. this allows sodium ions to diffuse from lumen into epithelial cells by facilitated diffusion
3. glucose / amino acid is taken with the sodium ion as it diffuses, in a specific carrier protein
4. glucose / amino acid exits cell into blood down a concentration gradient via facilitated diffusion

Question 8

what are endopeptidases

Answer 8

found in the stomach / ileum

hydrolyse peptide bonds between amino acids in the central region of a polypeptide

forming shorter polypeptides

Question 9

what are exopeptidases

Answer 9

found in the ileum

hydrolyse peptide bonds between terminal amino acids

forming dipeptides / amino acids

Question 10

what are dipeptidases

Answer 10

membrane bound enzymes

hydrolyse peptide bonds in dipeptides

forming amino acids

Question 11

what is the emulsification of lipids

Answer 11

bile salts break large lipid droplets into smaller ones, increasing the surface area

Question 12

what do lipases do

Answer 12

hydrolyse ester bonds in triglycerides

forming fatty acids, glycerol, monoglycerides

Question 13

how are lipids absorbed

Answer 13

1. bile salts stay associated with products of digestion forming micelles
2. micelles transport contents to epithelial cells where they dissociate
3. the non-polar products diffuse simply across the cell surface membrane
4. once inside, the smooth endoplasmic reticulum and golgi apparatus reform triglycerides, forming chylomicrons
5. chylomicrons are transported into lacteals via exocytosis before entering the blood