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ions and membrane potential

My question is why do cells have more potassium than sodium? why not the opposite? why they developed those pumps in favour of potassium? We need to go back and look at evolution.

Any help?

Reply 1

ash92:)

I can't remember enough to answer the question adequately, I'm afraid. But I will suggest some avenues for you to explore:

The sodium-potassium channel protein and how the proportion of Na vs K is maintained

The amount of energy required to open/close the Na or K channels

The size of the ions and charge:mass ratio

Other interactions (aside from influx and efflux) of the ions in the cell

Reply 2

Docjones1

I don't know exactly but I always though it was because if it pumped out 3 Sodium ions while pumping in 2 potassium ions the mass would be similar to before because potassium has a higher mass so you only need 2

Reply 3

Ahmed766

Original post by Daniel Atieh

My question is why do cells have more potassium than sodium? why not the opposite? why they developed those pumps in favour of potassium? We need to go back and look at evolution.

Any help?

It is due to the permeability of the voltage gated potassium ion and sodium ion pumps. I'm pretty sure the potassium ion channel is more permeable than the sodium ion channel. I hope this helped,

Reply 4

Docjones1

Original post by Ahmed766

It is due to the permeability of the voltage gated potassium ion and sodium ion pumps. I'm pretty sure the potassium ion channel is more permeable than the sodium ion channel. I hope this helped,

I think they're asking why the potassium ion channel is more permeable from an evoluntionary perspective, as opposed to sodium

Reply 5

Ahmed766

A fascinating hypothesis is that the high intracellular potassium concentration (and low sodium) is a remnant of the very first proto-cells that evolved on Earth. These cells had neither ion-tight membranes nor membrane pumps, so their intracellular environment would resemble that of the surroundings. The early, most basic cellular machineries thus evolved under ionic conditions similar to those in the primordial pond, but as life spread to different environments, cells evolved sophisticated pumps and transporters that allowed the maintenance of an intracellular solution similar to that found where life originated. Ref: http://www.pnas.org/content/early/2012/02/08/1117774109