Digestion of carbs and protein

Question 1

What are the principal dietary constituents?

Answer 1

Carbs
Protein
Fat

Vitamins
Minerals
Water

Question 2

What are the 3 hexose sugars we care about

or monosaccharides

Answer 2

Glucose
Galactose
Fructose

Question 3

What bond links two monosaccharides together to form a disaccharide?

Answer 3

Glycosidic bond

Question 4

What is lactose?

Answer 4

Disaccharide made up of Glucose and Galactose

Broken down by lactase

Question 5

What is Sucrose?

Answer 5

Disaccharide made up of Glucose and fructose

Broken down by sucrase

Question 6

What is Maltose?

Answer 6

Disaccharide made up of Glucose and glucose

Broken down by maltase

Question 7

What is the purpose of starch?

Answer 7

Plant storage form of glucose which comes in 2 types:

Amylose = glucose polysaccharide which is unbranched

Amylopectin = glucose chains that are highly branched

Question 8

What enzymes break down starch?

Answer 8

a-Amylase

Found in saliva and also released by pancreas

Question 9

What is cellulose?

What importance does bacteria have in its digestion?

Answer 9

Glucose polysaccharide with Beta 1-4 bonds (instead of a1-4) that makes up plant cell walls

Only bacteria present the enzyme ‘cellulase’ which can break it down

Question 10

How is glucose stored in animals?

Answer 10

Stored as glycogen

Question 11

What exists between epithelial cells in the digestive tract?

Answer 11

Tight junction complexes

Question 12

What does Na-K ATPase do?

How does this allow glucose to be absorbed?

Answer 12

1) Pumps sodium out of epithelial cell into blood, causing sodium to diffuse into the cell (from the lumen)
2) SGLT1 allows entry of Glucose alongside the Sodium thats coming into the cell

Question 13

What transporter allows Glucose to exit the epithelial cells and move into the blood?

Answer 13

Glut-2

Question 14

How is the absorption of fructose different to Glucose (and galactose)

Answer 14

Fructose moves into the epithelial cells through Glut-5 transporters

It then moves into the blood through Glut-2 proteins (same as glucose and galactose)

Question 15

What bonds hold amino acids together?

Answer 15

Peptide bonds

C - N

Question 16

What enzymes are responsible for the digestion of Proteins?

Answer 16

Proteases or peptidases

Question 17

What is the name given to the peptidase that cleaves large proteins into smaller chains (ie acts in the middle parts)?

Answer 17

Endopeptidase

Question 18

What is the name given to peptidases that act at the ends of peptide chains?

Answer 18

Exopeptidase

Question 19

What are the 2 types of exopeptidases and their differences?

Answer 19

Aminopeptidases & Carboxypeptidases

Aminopeptidases chop amino acids off at the Amino (NH2) end

Carboxypeptidases chop off amino acids at the carboxy end (COOH)

(basically they work at different ends of the chain)

Question 20

How is the transport of amino acids across epithelial cells similar to that of Glucose?

Answer 20

Both use the Na-K ATPase pump for their transport

Question 21

How is the transport of amino acids across epithelial membranes different to that of Glucose?

Answer 21

Each amino acid has a specific transporter to let it pass out of the epithelial cell

Amino acid transport also uses PROTON MOTIVE FORCE whereas Glucose doesnt