Biology – Control and coordination in plants | e-Consult
Control and coordination in plants (1 questions)
Login to see all questions.
Click on a question to view the answer
Auxin promotes cell elongation through a multi-step process involving proton pumps, cell wall acidification, and expansins. Here's a breakdown:
- Auxin Binding and Pump Activation: Auxin binds to its receptors, triggering the activation of H+-ATPases (proton pumps) in the plasma membrane.
- Proton Pumping: The activated pumps actively transport protons (H+) from the cytoplasm into the cell wall space.
- Cell Wall Acidification: The influx of protons leads to a decrease in pH within the cell wall, making it more acidic.
- Expansin Activation: The acidic environment activates expansin enzymes.
- Cell Wall Loosening: Expansins weaken the hydrogen bonds between cellulose microfibrils in the cell wall, increasing its plasticity.
- Turgor Pressure and Elongation: Increased turgor pressure within the cell, combined with the loosened cell wall, allows the cell to elongate.
Diagram (Conceptual):
A diagram would ideally show a plant cell with auxin binding to receptors, protons being pumped into the cell wall, the cell wall becoming more acidic, expansins binding to the cell wall, and the cell wall stretching under turgor pressure. This is difficult to represent in plain text, but the steps above outline the process.
Table summarizing the events:
| Step | Description |
| 1. Auxin Binding | Auxin binds to its receptors, activating proton pumps. |
| 2. Proton Pumping | H+ ions are pumped into the cell wall space. |
| 3. Acidification | The cell wall becomes more acidic. |
| 4. Expansin Activation | Expansin enzymes are activated. |
| 5. Cell Wall Loosening | Expansins weaken the cell wall structure. |
| 6. Elongation | Cell elongates due to turgor pressure and a flexible cell wall. |