Principles of Bioenergetics

Principles of Bioenergetics

A living cell operates a variety of metabolic functions, and to sustain this level of activity, it must obtain and burn energy. There is a continuous flow of energy in the cells and their surroundings in light energy or chemical energy. And it is stored inside the cell till the time of utilization in the form of ATP, an energy-storing molecule that stands for Adenosine Triphosphate. 

What is Bioenergetics?

Bioenergetics is the study of the many forms of energy changes that occur in living cells. Bioenergetics is a field of Biochemistry. Breaking the term as:

“Bio” means life and 

The term “energetics” refers to the attribute of something that is made up of energy.

Principles of Bioenergetics

From the word itself, it seems like it is related to energy. It obeys the laws of thermodynamics. The first law of thermodynamics and the second law of thermodynamics.

Let us Understand, one by one, both these laws and how these are applied in bioenergetics in biochemistry.

• The first law of Thermodynamics:

In simple words, it is the law of conservation of energy. It states that the total energy of any system is always constant, it can be changed from one form to another but can never be created nor destroyed.

ΔU=Q – W

Where,

ΔU =  Change in the Energy

Q =  Heat Added

W = Work done by the system

For example, When we do some work with our hands, our muscles are activated, and energy utilization and transformations occur there. The chemical energy in muscles gets transformed into mechanical energy. And how does that chemical energy in muscles come/generate? Simple, it is provided by the food we eat, which gets converted in the form of energy stored in our body and then utilized by cells. This way, bioenergetics follow the first law of thermodynamics.

• The second law of Thermodynamics:

The second rule of thermodynamics states that energy flows from a higher to a lower energy state, or heat travels from a warmer to a cooler body, not the other way around. The entropy of the system always increases or remains the same. 

For example, consider a person who does a workout in the gym. When his/her cells work, it will generate lots and lots of heat, and those heat will dissipate into surroundings. Thus increasing the entropy (here entropy can be said as the measure of the energy that is not available to allow cells to work) and there will come a time when there is no energy left in the system to allow cells to work until more energy is generated. This is the relation of the second law of thermodynamics with bioenergetics.

The first and second laws state the conservation and transfer of energy from one form to another, respectively. And the concepts of both the laws are used in an expression as 

                                             ΔH= ΔG + TΔS

Rearranging as 

ΔG=ΔH – TΔS

Where,

ΔG  = Gibbs free Energy

ΔH   = Change in Enthalpy

ΔS  = Change in Entropy

T = Temperature in kelvin

Here, Gibbs free energy can be said as the amount of energy capable of doing work. This equation can tell us the direction of a bioenergetic reaction in biochemistry and the spontaneity of a reaction as

If   is negative, the process is spontaneous and the reaction is an exergonic reaction.

If   is positive, the process is nonspontaneous and the reaction is endergonic.

And if  is zero, the process or the reaction has reached equilibrium.

If we speak in terms of bioenergetic reactions in biochemistry, 

Both spontaneous and non-spontaneous reactions are possible. The relative free-energy levels of the reactants and products define the ratio of reactants to products present at equilibrium. G has a negative value as long as the total free energy of the reactants is larger than the total free energy of the products, and the reaction progresses in the direction of product production. The bigger the G, the farther the reaction is from equilibrium, and the more work the system can accomplish following the principles of bioenergetics.

Conclusion

Bioenergetics is the study of processes performed by living organisms, how the energy transformation, collection, and consumption takes place inside the cells, tissues, and organisms. The two principles of bioenergetics governing its processes are the First and the Second Law of thermodynamics used with the concept of Gibbs free energy. Gibbs free energy allows us to understand the spontaneity and the direction of the reaction. 

In Summary, The transition of potential to kinetic energy and vice versa is the main focus of bioenergetic processes. Metabolic reactions, which are essential to the operation of every biological system, represent such energy transformation.