Digestion of Carbs and Proteins

Question 1

What breaks down disaccharides in the small intestine?

Answer 1

Brush border enzymes on the surface

Question 2

3 main polysaccharides

Answer 2

Starch
Glycogen
Cellulose

Question 3

Two types of starch

Answer 3

a-amylose

amylopectin

Question 4

Structure of amylose

Answer 4

straight chains of glucose

Question 5

Structure of amylopectin

Answer 5

Highly branched chains

Question 6

What are the bonds found in cellulose

Answer 6

beta-1,4 glycosidic bonds

Question 7

Why does lactose intolerance cause its symptoms?

Answer 7

Unabsorbed lactose causes an osmotic gradient in the lumen, pulling water into it

Question 8

What is glucose-galactose absorption syndrome?

Answer 8

Lack of expression of transport proteins, meaning those sugars cannot be absorbed

Question 9

What membrane contains the microvilli of the small intestine?

Answer 9

Apical membrane

Question 10

Transcellular transport requires how many transport proteins? Do they work both ways?

Answer 10

2
1 for in
1 for out
Unidirectional

Question 11

What pathway occurs around cells?

Answer 11

Paracellular pathway

Question 12

What is the biosynthetic pathway?

Answer 12

Production of proteins inside the cell to then be transported out (RER -> Golgi -> out)

Question 13

What is vectorial transport?

Answer 13

Transport of molecules in or out the cell, which can only occur in one direction

Question 14

What is the basolateral membrane?

Answer 14

The underside/outside of small intestine cells

Question 15

How is glucose transported INTO intestinal cells?

Answer 15

Coupled with Sodium for SGLT1

Question 16

What is SGLT1

Answer 16

Sodium coupled glucose transport enzyme

Question 17

How is glucose passed from the cell to the blood?

Answer 17

GLUT-2 transport protein

Question 18

What does SGLT1 transport?

Answer 18

Glucose AND galactose coupled with Na

Question 19

How is an inward sodium gradient maintained in intestinal cells?

Answer 19

Na-K ATPase

Question 20

Why does H20 readily follow glucose into the blood?

Answer 20

Large inflow of Na into the blood causes an osmotic gradient to form
Water easily passes through tight junction

Question 21

How does fructose pass from lumen to the cell?

Answer 21

GLUT-5 protein

Question 22

Why doesnt fructose require a transporter?

Answer 22

We don’t have a blood fructose level, so fructose always flows in

Question 23

Why does water not follow fructose into the blood stream?

Answer 23

No Na transported with the fructose so no concentration gradient is formed

Question 24

What does GLUT-5 transport?

Answer 24

Fructose (out of cell)

Question 25

What does GLUT-2 transport?

Answer 25

Fructose, glucose and galactose (out of cell)

Question 26

What do proteases do?

Answer 26

Hydrolyse peptide bonds (break down proteins to amino acids)

Question 27

What is the function of endopeptidases?

Answer 27

Break peptide bonds in the middle of proteins

Question 28

What are exopeptidases?

Answer 28

Break amino acids off the ends of proteins

Question 29

What is an aminopeptidase?

Answer 29

An exopeptidase which breaks an AA off the amino end

Question 30

What is a carboxypeptidase?

Answer 30

An exopeptidase which breaks an AA off the carboxy end

Question 31

How are single amino acids transported from the lumen to the cell?

Answer 31

Sodium coupled amino acid transporter

Question 32

How are 70% of amino acids taken up?

Answer 32

Di-/tripeptides

Question 33

How are tri-/dipeptides taken from the lumen to the cell?

Answer 33

PepT1

Protein coupled transport protein

Question 34

How is the acidic microclimate of the lumen maintained?

Answer 34

NHE3

Pumping of protons out of the cell back into the lumen in exchange for a Na