Diffusion of ions across membranes through specific ion channels is driven by

Passive transport is the driving force to diffuse ions through channels specific to them across the membrane down their concentration gradient.

Further Explanation:

The passive transport which occurs with the help of transporter proteins or channel proteins embedded within the membrane is called facilitated diffusion. In this type of diffusion, the ion to be transported binds to its specific ion channel which mediates its transportation. Facilitated diffusion being passive in nature does not require ATP as an energy source, rather, the ions or molecules travel to their lower concentration from higher concentration regions via the membrane displaying their diffusive nature. Simple diffusion differs from facilitated diffusion as it is not dependent on the binding of ions to the channel protein.

During facilitated diffusion, the ion binds to the transporter protein on either side of the membrane depending on the concentration gradient. This leads to a conformational change in the transporter protein which causes exposure of the ion to the other side of the membrane. Once exposed to the new side, the ions get dissociated from the protein channel resulting in its reorientation so that the cycle can repeat and more ions can be transported until the gradient is there.

The direction of transport occurs generally to the side where the ion concentration is comparatively lower than the other side forming a gradient. For example, glucose is transported through glucose transporter inside the cell where it transforms into glucose-6-phosphate. Due to this conversion, a concentration gradient always remains intact which favors glucose transport into the cell cytoplasm.

Learn more:

1. Learn more about meiosis

2. Learn more about the process of molecular diffusion in a cell

3. Learn more about human sperm and egg cell

Answer Details:

Grade: High School

Subject: Cell Biology

Chapter: Membrane Transport

Keywords:

Membrane transport, diffusion, facilitated diffusion, passive transport, concentration gradient, channel proteins, transporter proteins, glucose transporter.