How does a concentration gradient provide energy?

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SUMMARY

The discussion centers on the role of concentration gradients in providing energy for processes such as ATP synthesis and secondary active transport. It highlights that the hydrogen ion gradient drives ATP synthase and that energy is derived from the movement of ions from areas of high concentration to low concentration. The Nernst Equation is referenced to explain the relationship between concentration gradients and energy, emphasizing that when concentrations are equal, no energy is produced. Additionally, the discussion notes the importance of considering electric potential and chemical activities in biological systems.

PREREQUISITES
  • Understanding of ATP synthase and its function in cellular respiration.
  • Familiarity with the Nernst Equation and its application in electrochemistry.
  • Knowledge of Gibbs free energy and its relevance to concentration gradients.
  • Basic concepts of ionic strength and chemical activity in biological systems.
NEXT STEPS
  • Study the Nernst Equation in detail and its implications for ion transport.
  • Explore the mechanisms of ATP synthesis in mitochondria and chloroplasts.
  • Investigate the principles of secondary active transport and its biological significance.
  • Learn about the role of electric potential in cellular processes and membrane dynamics.
USEFUL FOR

Biochemists, cellular biologists, and anyone interested in understanding energy transfer mechanisms in biological systems.

sameeralord
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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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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?
 
This response may be true if these ions were free.
There are unfortunately hydrated.
 
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.
 
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.
 

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