Question

Researchers often use light-controlled proteins to activate or turn on/off various systems. Originally channelrhodopsin was found to be a non-specific cation ion channel. It has been modified by researchers to allow only specific ions in and out of the cell. 

6a) Diagram what you would expect the action potential to look like after shining light on a neuron expressing native channelrhodopsin(A) (attach a computer-generated image or one from your phone camera etc, needs to be legible and labeled). Explain your reasoning for why it should look this way.  

6b) Diagram what you would expect to happen with modified channels that specifically allow sodium in and potassium out when light is shining on the neuron (B). Explain your reasoning for why your action potential should look this way 

Answer 1

The action potential look like the shining potential to neurons.

The shining light on the neuron expressing the rhodopsin A:

Channel rhodopsin activates neurons while halorhodopsin silences them. Once the light is falling the neuron, it activates the other triggering reaction, Hence this would cause multiple triggers. The shining light would cascade the series of chemical reactions making the various other reaction to happen. This is basically the ligand-gated channel. Even the shining light of a few milliseconds is very crucial to bring drastic changes.  

So hence in that diagram, when light falls on the photoreceptor, it makes the opening of the protein receptor and makes the movement of the ligand into the system. Hence the A shows the equal movement of the ions in and out of the cell

The action potential in the case of B.

The B shows, based on the concentration gradient there is the movement of the molecules. The movement of nutrients makes the ions move in and out through the receptor. This movement is from higher concentration to lower concentration. Hence this can lead to better activity of the cell and maintain the cellular pathway.