The carrier proteins span the plasma membrane and bind to the molecule or ion being transported.
The molecule binds to the receptor sites on the carrier protein.
The ATP binds to the protein causing it to split into ADP and a phosphate molecule. This causes the protein to change shape and it opens at the other end to let the molecule out.
The molecule is now released on to the other side of the membrane.
The phosphate molecule is also released and the protein reverts back to it's original shape and the phosphate molecule recombines with the ADP to form ATP.
1 of 2
Remember!
Active transport needs ATP because it goes against a concentrated gradient.
Facilitated diffusion occurs down a concetrated gradient and so does not need metabolic energy to help it do so.
Comments
No comments have yet been made