4.4 Active transport

Question 1

What is active transport?

Answer 1

Movement of molecules from an area of lower concentration to an area of higher concentration, which requires metabolic energy/ATP/carrier protein.

Question 2

In active transport, what is ATP used to?

Answer 2

1. directly transport molecules
2. co-transport (individually transport molecules using a concentration gradient which has already been set up by active transport)

Question 3

How is active transport differ from passive diffusion?

Answer 3

ATP:
1. requires ATP
2. moves against the concentration gradient

Passive diffusion:
1. doesn’t require ATP
2. moves down the concentration gradient

Question 4

How is active transport differ from facilitated diffusion?

Answer 4

ATP:
1. requires ATP
2. moves against the concentration gradient
3. only involves with carrier protein

Facilitated diffusion:
1. doesn’t require ATP
2. moves down the concentration gradient
3. involves with channel protein and carrier protein

Question 5

How does active transport work?

Answer 5

1. carrier protein spans (跨越) the membrane and binds to the molecule/ion
2. the molecule binds to the receptor site on carrier protein
3. ATP binds to the carrier protein and splits into phosphate and ADP by hydrolysis
4. as a result, the carrier protein changes shape and opens to the opposite side of the membrane
5. the molecule/ion is released to the other side of membrane
6. the phosphate is released from the carrier protein which causes it to revert to its original shape
7. the phosphate recombines with ADP to form ATP by respiration

Question 6

Can carrier proteins be used for every transportation?

Answer 6

No, each carrier protein can only transport one type of molecule/ion.