4. More on Active Transport

Question 1

Describe how co-transport helps absorb glucose?

Answer 1

Glucose is absorbed into bloodstream in small intestine.
In The mammalian ileum (final part of mammal’s small intestine) the concentration of glucose is too low for glucose to diffuse out into the blood.
So, glucose absorbed from lumen (middle) of the ileum by co-transport.

Question 2

Step 1

Answer 2

• sodium ions actively transported out of epithelial cells into ileum , into the blood. By sodium potassium pump.
• this creates conc gradient - higher conc of sodium ions in lumen of ileum that inside cell

Question 3

Step 2

Answer 3

• sodium ions then diffuse from Lumen into epithelial cell down their conc gradient. Via the sodium-glucose co-transporter proteins
• co transporter carried glucose into cell with sodium
• as a result the conc of glucose inside cell increases

Question 4

Step 3

Answer 4

•glucose diffuses out of cell into blood down its conc gradient through a profile channel by FD

Question 5

Who’s concentration gradient does the co transporter use

Answer 5

Sodium ions

to move another molecule against its conc gradient - glucose

Question 6

What is rate of active transport affected by ?

Answer 6

Speed of individual carrier proteins - faster the faster fate of AT.

Number of carrier proteins - more profile the faster rate of AT.

Rate of respiration in cell and availability of ATP
If respiration is inhibited AT can’t take place