Nutrient Digestion I (Carbohydrates and Proteins)

Question 1

What are the three monosaccharides?

Answer 1

Glucose
Galactose
Fructose

Question 2

What three digestive enzymes are expressed on the surface of the small intestine?

Answer 2

Lactase
Sucrase
Maltase

Question 3

What does Lactase break Lactose down into?

Answer 3

Glucose & Galactose

Question 4

What does Sucrase break Sucrose down into?

Answer 4

Glucose & Fructose

Question 5

What does Maltase break Maltose down into?

Answer 5

Glucose & Glucose

Question 6

What happens to those people who can’t express Lactase?

Answer 6

The Lactose sits in the lumen of the tube causing water to be drawn in and causing osmotic diarrhoea

Question 7

What is Amylopectin?

Answer 7

A highly branched glucose chain joined by alpha-1,4 glycosidic bonds

Question 8

What is alpha-amylose?

Answer 8

Glucose linked in straight chains joined by α-1,4 Glycosidic bonds

Question 9

What is Cellulose?

Answer 9

Unbranched, linear chains of Glucose joined by β-1,4 Glycosidic bonds

Question 10

What is Glycogen?

Answer 10

Similar to α-amylose with Glucose being linked by α-1,4 Glycosidic bonds

Question 11

How much Glycogen is stored in the liver at one time?

Answer 11

18 miles worth of running

Question 12

What type of epithelium lines the small intestine?

Answer 12

Monolayer of columnar epithelial cells

Question 13

What are the two membranes of the intestine and what is it lined with?

Answer 13

Top - Apical on the outside and it has microvilli on on the villi itself
Bottom & Side - Basolateral

Question 14

What type of junctions exist between the basolateral membranes?

Answer 14

Tight junctions

Question 15

What does paracellular indicate?

Answer 15

Around or between cells - Must be smaller than Glucose to do so e.g. Water

Question 16

What does Glucose require for passing through a cell?

Answer 16

Two transport proteins

Question 17

What is needed as well as Glucose for it pass through a cell?

Answer 17

Sodium is required with the use of a symporter (SGLT1)

Question 18

How does the Glucose symporter work?

Answer 18

Works by secondary active transport from the gradient made by the Na/K pump

Question 19

Why is no symporter needed to carry Fructose over the apical membrane?

Answer 19

The small intestine is enriched with GLUT-2 protein that transports it across
No water advantage because of no Na

Question 20

What transports Glucose, Fructose and Galactose over the basolateral membrane?

Answer 20

GLUT-2 carrier found on the basolateral membrane

Question 21

What can proteins undergo to create Glyco/Lipoproteins?

Answer 21

Post-translational modification

Question 22

What hydrolyse peptide bonds to form Amino Acids?

Answer 22

Proteases and Peptidases

Question 23

What do endopeptidases do?

Answer 23

Split proteins into two smaller fragments by working in the interior portion of the protein

Question 24

What do exopeptidases do?

Answer 24

Act on exteriors of the protein to break off small fragments bit by bit

Question 25

How do Amino Acids cross the apical membrane?

Answer 25

Use of a symporter similar like that of Glucose and Na Driven the same way by the Na/K pump

Question 26

How do Amino Acids cross the basolateral membrane?

Answer 26

Separate transporter

Question 27

How do most Amino Acids enter the body?

Answer 27

As di/tri peptides

Question 28

How do these di/tripeptides enter the body?

Answer 28

Via the Proton motive force as they use a hydrogen ion

PepT1 is Hydrogen bound

Question 29

What force drives the di/tripeptide entering the cell?

Answer 29

Na/K pump

Question 30

As the Hydrogen leaves the cell what does it create?

Answer 30

Acid Microclimate as it gets stuck in the mucus as it leaves

Question 31

What causes the hydrogen to leave the cell?

Answer 31

The Na/H exchanger

Question 32

Is Penicillin a tripeptide? If so, what is it’s substrate?

Answer 32

Yes

PepT1