Cell Membranes- Active Transport

Question 1

How is active transport similar to diffusion?

Answer 1

Carrier proteins are involved, molecule attaches, protein changes shape, releases molecule on other side of membrane

Question 2

What are the main differences between active transport and facilitated diffusion?

Answer 2

• Active transport is from a low to high concentration

- Active transport requires energy

Question 3

What are co-transporters?

Answer 3

A type of carrier protein

Question 4

What do co-transporters do?

Answer 4

Bind to 2 molecules at a time and concentration gradient of one of the molecules is used to move the other molecule against its own concentration gradient

Question 5

What are the three factors affecting the rate of active transport?

Answer 5

Speed of individual carrier proteins, number of carrier proteins present, rate of respiration in cell and availability of ATP

Question 6

What happens in the small intestine?

Answer 6

Glucose is absorbed into the bloodstream

Question 7

How does co-transport occur?

Answer 7

Concentration of glucose in the ileum is too low for glucose to diffuse out into the blood so glucose is absorbed from lumen of the ileum by co-transport

Question 8

What is the process of co-transport?

Answer 8

1. Sodium ions actively transported out of ileum epithelial cells into blood by sodium-potassium pump which creates a concentration gradient as there’s a higher concentration of sodium ions in lumen of ileum than inside cell
2. Causes sodium ions to diffuse from lumen of ileum into epithelial cell down concentration gradient via the sodium-glucose co-transporter proteins
3. Co-transporter carries glucose into cell with sodium so concentration of glucose inside cell increases
4. Glucose diffuses out of cell into blood down concentration gradient through protein channel by facilitated diffusion