3.3 Digestion and Absorption

Question 1

what is digestion

Answer 1

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

Question 2

what are digestive enzymes

Answer 2

extracellular

Question 3

three main types of digestive enzymes

Answer 3

carbohydrases, proteases, lipases

Question 4

where does digestion of carbohydrates occur

Answer 4

mouth and small intestine

Question 5

what does amylase do

Answer 5

break down (hydrolyses) starch into maltose

Question 6

what enzyme hydrolyses maltose into glucose

Answer 6

maltase

Question 7

where is amylase made

Answer 7

salivary glands, pancreas and small intestine

Question 8

what is maltase

Answer 8

• disacharridase , found in cell surface membranes of epithelial cells lining in small intestine

Question 9

what do disaccharidases allow

Answer 9

absorption of monosaccharides into epithelial cells of small intestine which pass them into the blood stream

Question 10

where does protein digestion occur

Answer 10

lumen of stomach by proteases

Question 11

what does endopeptidase do

Answer 11

hydrolyses peptide bonds within proteins, creating smaller sized proteins
- This enzyme is secreted along with hydrochloric acid, meaning the pH in the stomach is low and therefore acidic
The partially digested food moves from the stomach into the small intestine

Question 12

what neutralises the acidic mixtures from the hydrolysis of proteins

Answer 12

pancreatic juice containing endopeptidases and exopeptidases

Question 13

what does an exopeptidase do

Answer 13

hydrolyse peptide bonds at the ends of polypeptide chains to produce dipeptides

Question 14

what does an endopeptidase do

Answer 14

hydrolyse peptide bonds within polypeptide chains to produce dipeptides

Question 15

where are dipeptidases found

Answer 15

cell surface membrane of the epithelial cells in the small intestine

Question 16

what do dipeptidases do

Answer 16

hydrolyse dipeptides into amino acids which are released into the cytoplasm of the cell

Question 17

what happens to lipids before digestion

Answer 17

emulsification

Question 18

what happens during emulsification

Answer 18

• solid lipids are converted to (fatty acid droplets) in the stomach
• bile is secreted once fatty acid arrives at small intestine
• breaks fatty acids into smaller ones via emulsification

Question 19

what does emulsification do

Answer 19

helps to increase the surface area of the fatty droplets for action of digestive enzymes

Question 20

where is bile made

Answer 20

liver

Question 21

where is bile stored

Answer 21

gall bladder

Question 22

where does lipid digestion take place

Answer 22

lumen of small intestine

Question 23

what enzyme break down lipids

Answer 23

lipases

Question 24

what do lipases break lipids down to

Answer 24

glycerol and fatty acids
(monoglycerides)

Question 25

where are lipase enzymes produced

Answer 25

pancréas

Question 26

when are amino acids transported

Answer 26

when there are sodium ions present (co transport)

Question 27

how are amino acids transported

Answer 27

For every sodium ion that is transported into the cell, an amino acid is transported in This occurs via facilitated diffusion, which requires the movement of molecules down their concentration gradient

Question 28

how do amino acids pass into capillaries

Answer 28

via facilitated diffusion

Question 29

how is concentration gradient of sodium ions from lumen into epithelial cell maintained

Answer 29

by the active transport of sodium ions out of the cell and into the blood via a sodium-potassium pump at the other end of the cell

Question 30

how are sodium ions and glucose ions co transoorted

Answer 30

facilitated diffusion

Question 31

where do the glucose molecules go after being contransoroted

Answer 31

glucose molecules diffuse across the epithelial cell and enter the capillary at the other end of the cell by facilitated diffusion

Question 32

how is concentration of sodium ions maintained

Answer 32

actively transporting sodium ions out of epithelial cells into the blood

Question 33

how are micelles formed

Answer 33

monoglycerides and fatty acids associating with phospholipids and bile salts

Question 34

what do micelles do

Answer 34

break down and add to a pool of fatty acids and monoglycerides that are dissolved in the small intestine solution surrounding the epithelial cells - enter cell via diffusion

Question 35

why is micelles being non polar important

Answer 35

diffuse through phospholipid booster

Question 36

what the longer fatty acid chains do

Answer 36

recombine with monoglycerides and glycerol to form triglycerides in endoplasmic reticulum