Active Transport

Question 1

What is active transport?

Answer 1

Net movement of molecules / ions across plasma membranes using energy from ATP, against a concentration gradient via a carrier protein

Question 2

What do co-transporters do?

Answer 2

Bind two molecules at a time. The concentration gradient of one of the molecules is used to move the other molecule against its own concentration gradient

Question 3

Co-transport and absorption of glucose

Answer 3

• Sodium ions are actively transported out of the epithelial cells in the ileum, into the blood by the sodium-potassium pump
• This creates a concentration gradient, causing sodium ions to diffuse down their concentration gradient and glucose to be transported against its concentration gradient (via the sodium-glucose co-transporter proteins)
• Increased concentration of glucose inside the cell
• Glucose diffuses out of the cell, into the blood, down its concentration gradient, through a protein channel by facilitated diffusion

Question 4

How does speed of individual carrier proteins affect rate of active transport?

Answer 4

The faster they work, the faster the rate of active transport

Question 5

How does number of carrier proteins affect rate of active transport?

Answer 5

The more proteins there are, the faster the rate of active transport

Question 6

How does rate of respiration in the cell affect rate of active transport?

Answer 6

As rate of respiration decreases, availability of ATP is limited, limiting energy for active transport to occur, decreasing rate of active transport