[Unit 4.4] | Active Transport

Question 1

What is Active Transport?

Answer 1

Moving substances across a membrane against the concentration gradient (Low -> High Conc) using ATP for external energy and carrier proteins as pumps.

Question 2

Describe the process of Active Transport after a cell binds to a carrier protein.

Answer 2

• The molecule binds to receptor sites.

• ATP inside the cell binds to the carrier.
• The ATP splits into a phosphate molecule and ADP.
• The protein therefore changes shape and releases the molecule into the cell.

• The phosphate molecule is then released from the carrier so it can revert to its original shape.
• (The phosphate recombines with ADP to form ATP during respiration).

Question 3

What is a sodium-potassium pump?

Answer 3

• A sodium potassium pump is made up of 2 protein carriers that transport sodium and potassium respectively.
• It actively transports sodium ions out of a cell at the same time as potassium ions are actively transported into a cell.
• 3 sodium ions are transferred per 2 potassium ions (to maintain the electrochemical gradient).
• It is vital to many processes in organisms, including the creation of nerve impulses.