How does a concentration gradient provide energy?

In summary, The hydrogen ion gradient drives ATP synthase, while in secondary active transport, the preexisting concentration gradient provides energy to transport molecules. This energy is a combination of the Gibbs energy for concentration and the electric potential generated by the charged species. When the concentration on each side is equal and there is no electric potential, there is no energy. However, it is important to consider the difference in chemical activities and ionic strength when applying the Nernst Equation to explain the energy source in biological systems. The Nernst Equation was originally created for chemical redox reactions and may not accurately give a number for the energy in biological processes.
  • #1
sameeralord
662
3
Ok hydrogen ion gradient drives ATP synthase. In secondary active transport the preexisting concentration gradient drives the molecules.

My question is what do they mean when they say concentration gradient provides energy to do this. Is it the movement of ions like hyrdogen from high to low that results in energy.

When the concentration on each side is the same why is there no energy!

Thanks! :smile:
 
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  • #2
DeltaG = RTln(c1/c2)
or
DeltaG = 2.303RTlog10(c1/c2)

You must also consider the fact that these species are charged. This generates an electric potential in addition to the gibbs energy for concentration.

DeltaG = 2.303RTlog10(c1/c2) + ZFdeltaV

where deltaV is the potential in volts across the membrane, Z is the charge and F is the faraday.

What happens when c1 is equal to c2 and deltaV = 0?
 
  • #3
This response may be true if these ions were free.
There are unfortunately hydrated.
 
  • #4
Yeah you have to take into account the difference in chemical activities, in ionic strength, etc. It's not a trivial thing.

That said, the aforementioned Nernst Equation is sufficient to explain where the energy's coming from, just not accurately give a number for it.
 
  • #5
The Nernst Equation was created for chemical redox reactions for battery cells.
http://en.wikipedia.org/wiki/Nernst_equation
That has nothing to see with biology. The ions gradients are coming from the same specie and do not implie a redox reaction of any kind.
Of course Biology took the original theory and tried to apply it to cell.
 

1. How does a concentration gradient provide energy?

A concentration gradient provides energy through the process of diffusion. Diffusion is the movement of particles from an area of high concentration to an area of low concentration. This movement of particles creates a flow of energy, which can be harnessed for various processes.

2. What is the role of a concentration gradient in biological systems?

In biological systems, a concentration gradient is crucial for processes such as cellular respiration, photosynthesis, and the transport of nutrients and waste products. The concentration gradient provides the necessary energy for these processes to occur.

3. How is the energy from a concentration gradient converted into usable forms?

The energy from a concentration gradient is converted into usable forms through the process of ATP synthesis. ATP (adenosine triphosphate) is a molecule that stores and releases energy for cellular processes. The movement of particles down a concentration gradient is coupled with the production of ATP, which can then be used for various cellular functions.

4. Can a concentration gradient be artificially created?

Yes, a concentration gradient can be artificially created through methods such as osmosis, dialysis, and electrodialysis. These processes involve the movement of particles across a semi-permeable membrane, creating a difference in concentration on either side of the membrane.

5. How does the magnitude of a concentration gradient affect the amount of energy produced?

The magnitude of a concentration gradient directly affects the amount of energy produced. A larger concentration gradient results in a greater flow of particles and therefore, a greater amount of energy being released. This is why biological processes that require a large amount of energy, such as muscle contraction, have a high concentration gradient in order to meet the energy demands.

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