Primary/Secondary Active Transport

Question 1

What is primary active transport?

Answer 1

• Involves the movement of ions/molecules against their concentration gradient with the direct use of ATP to power the process.
• The carrier proteins involved in this processes are called ‘pumps’

Question 2

What is an example of primary active transport?

Answer 2

• proton pumps
• They pump H+ ions across a membrane against their concentration gradient.

Question 3

SODIUM-POTASSIUM PUMP

Answer 3

• Sodium enters the cell. 3 sodium ions bind, the protein is phosphoralated, ATP transfers its phosphate the protein. Changes the shape of the protein
• The ATP is then attached to the sodium and then hydrolysed
• The sodium ions are pushed to the outside of the cell.
• The potassium enters the inside of the cell.
• Two potassium ions bind - phosphate group is released from the protein
• The potassium is dropped off, room for 3 sodium ions. The cycle repeats

Question 4

What is secondary active transport?

Answer 4

• It is when a concentration gradient established by a transmembrane pump, such as the proton pump, is used to move another molecule into the cell against its concentration gradient.

Question 5

What happens in secondary active transport?

Answer 5

• The 3 sodium ions enter the cell and the glucose molecules also enter the cell.