Chapter 9.1

Question 1

Describe the general characteristics of Glut 2

Answer 1

• low affinity transporter in hepatocytes and pancreatic cells
• > Glut 2 captures the excess glucose primarily for storage
• > when the glucose [] drops below the Km of the transporter, the remainder bypasses the liver and enters peripheral circulation

Question 2

How does the high Km value of Glut 2 relate to how much glucose the liver can pick up

Answer 2

• high Km means that the liver will pick up glucose in proportion to its concentration in the blood
• > so first-order kinetics

Question 3

Describe the general characteristics of Glut 4

Answer 3

• in adipose tissue and muscle
• > responds to glucose concentration in peripheral blood
• > rate of glucose transport is increased by insulin
• > more Glut 4 transporters appear on the surface of cells

Question 4

How does the Km value of Glut 4 relate to how much glucose the transporter can take

Answer 4

• Km of Glut 4 is close to normal glucose blood levels
• this means that the transporter is saturated when blood glucose levels are higher than normal
• > therefore, these transporters will only permit a constant rate of glucose influx
• > resulting in zero order kinetics

Question 5

How does adipose tissue store glucose

Answer 5

• requires glucose to form dihydroxyacetone phosphate

- >DHAP is converted to glycerol phosphate to store incoming fatty acids as triacylglycerols