4.4 Active transport

Question 1

What is active transport?

Answer 1

the movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins.

Question 2

How is ATP used in active transport?

Answer 2

• to directly move molecules

- to individually move molecules using a set up concentration gradient by direct AT (cotransport)

Question 3

How does active transport differ from other forms of transport?

Answer 3

• metabolic energy is needed
• substances are moved against the concentration gradient
• carrier proteins are involved; acting as pumps
• it is a very selective process

Question 4

Describe the direct active transport of a single molecule/ion.

Answer 4

1) the carrier protein spans the membrane and binds to the molecule/ion on one side
2) the molecule/ion binds to receptor sites on the carrier protein
3) On the inside of the cell/organelle, ATP binds to the protein, causing it to split into ADP and a phosphate molecule. this causes the protein molecule to change shape and open the opposite side of the membrane.
4) the molecule/ion is released onto the other side
5) the phosphate is released from the protein which causes it to revert to its original shape.

Question 5

Describe a sodium-potassium pump.

Answer 5

• when sodium is ions are removed from the pump, potassium ions are entering it.