Question #670a6
1 Answer
May 20, 2017
Auxin hormones influences the acidity of the cell wall, which indirectly determines the elasticity of the wall.
Explanation:
Plant cell walls need to be elastic so specific cells can grow in length so that the plant bends towards a light source and maximize the amount of light received.
According to acid growth hypothesis, auxin (a plant hormone) stimulates the proton pumps in the membrane of the plant cell. The pumping of hydrogen ions across the membrane lowers the pH in the cell wall (it becomes more acidic). The acidic conditions trigger expansin proteins that break the hydrogen bonds between the various molecules that comprise the wall. Basically, the cell wall becomes looser as a result, allowing the cell wall to become more acidic.
