Digestion

Question 1

What is digestion?

Answer 1

The hydrolysis (by enzymes) of large molecules into smaller molecules that can be absorbed and assimilated

Question 2

What does assimilated mean

Answer 2

Absorbed and used by the body

Question 3

What enzyme breaks down starch in the mouth?

Answer 3

Salivary amylase ; it breaks the glycosidic bonds in starch to produce maltose

Question 4

What enzyme breaks down starch in the duodenum?

Answer 4

Pancreatic amylase
Breaks down starch into maltose

Question 5

What enzyme breaks down starch in the ileum

Answer 5

Maltase
Breaks down maltose into glucose

Question 6

Where does salivary amylase come from? (mouth)

Answer 6

Salivary glands release saliva which contains salivary amylase

Question 7

What does the pancreas release?

Answer 7

Fluid which contains pancreatic amylase

Question 8

Where does the compete hydrolysis of starch to glucose occur?

Answer 8

in the ileum (in the small intestine)

Question 9

Small intestines ileum

Answer 9

The ileum contain villi (folded mucosa)
Epithelial layer made up of lmay epithelial cells

Question 10

What are membrane-bound disaccharides
(on the epithelial cell membrane)

Answer 10

The enzymes (disaccharides) are not released into the lumen but instead are part of the cell surface membrane

Question 11

What does the liver produce?

Answer 11

Bile

Question 12

WhT does the gall bladder do ?

Answer 12

Stores bile

Question 13

What is the duodenum

Answer 13

The first part of the small intestine

Question 14

What does the duodenum do?

Answer 14

Digestion of lipids occurs there

Question 15

What does the pancreas produce ?

Answer 15

Produces lipase

Question 16

What breaks down lipids in the duodenum?

Answer 16

Bile salts emulsify fats
Increase the surface area
Faster digestion by pancreatic lipase

Question 17

What else breaks down lipids in the duodenum

Answer 17

Lipase
Breaks down fats unit glycerol and 3 fatty acids

Question 18

What is lipase?

Answer 18

Enzyme secreted by pancreas into small intestine

Question 19

What does lipase do?

Answer 19

Hydrolyses ester bonds of triglycerides to produce :
glycerol
fatty acids
monoglycerides (glycerol + 1 fatty acid)

Question 20

What is bile?

Answer 20

An alkaline fluid released to small intestine via bile duct

Question 21

What does bile contain?

Answer 21

Bile salts

Question 22

What do bile salts do?

Answer 22

They emulsify lipids into small droplets (=physical process)
—> breaking them into small droplets increases the surface area
—> this allows a faster hydrolysis by lipase

Question 23

where is bile made?

Answer 23

Made in the liver

Question 24

Where is bile stored?

Answer 24

In the gall bladder

Question 25

How does bile get the the small intenstine?

Answer 25

Passes down the bile duct

Question 26

What is the benefit of bile being alkaline?

Answer 26

It neutralised acidity from the stomach —> optimum pH for pancreatic enzymes

Question 27

What is the process of lipid digestion?

Answer 27

- Bile salts emulsify fats -Lipase enzyme released from the pancreas hydrolyses ester bonds - This forms monoglycerides/fatty acids/glycerol in the small intestine

Question 28

What are the 3 protein enzymes for protein digestion

Answer 28

Endopeptidases Exopeptidases Dipeptidases

Question 29

What is the role of endopeptidases?

Answer 29

endo= within,inner Pepsin in the stomach is secreted with HCL **Hydrolyses **internal** peptide bonds within proteins** This creates smaller sized protein ‘chunks’ **Produces small polypeptides and peptides** **Produced shorter chains**

Question 30

What is the optimum pH of HCL

Answer 30

pH 1-2

Question 31

What is the role of exopeptidases?

Answer 31

exo = outside, outer, external Pancreatic juice contains endopeptidases and exopeptidases Hydrolyses **terminal (last)** peptide bond at either end Removes individual amino acids Also produced dipeptides at the end

Question 32

What are dipeptidases?

Answer 32

Membrane-bound enzymes Located in the microvilli of epithelial cells of ileum

Question 33

What do dipeptidases do?

Answer 33

Hydrolyse dipeptides Produce amino acids

Question 34

How do endo and exopeptidases increase the efficiency of hydrolysis

Answer 34

endo —> hydrolyses internal peptide bonds to produce shorter chains Exo —> more ‘ends’ to hydrolyse terminal peptide bonds

Question 35

How are proteins digested in the duodenum?

Answer 35

Pancreatic endo and exopeptidase are present Exopeptidase breaks down external peptide bonds in proteins To produce dipeptides and amino acids

Question 36

How are proteins digested in the stomach ?

Answer 36

Endopeptidase (pepsin) Breaks internal peptide bonds in proteins to produce smaller polypeptide chains

Question 37

How are proteins digested in the ileum?

Answer 37

Dipeptidase Breaks down dipeptides into amino acids