Hello everyone, I am Dr. Ujwalkumar Trivedi, Head of Biotechnology Department at Marwadi University Rajkot. I teach Molecular Biology to the students of M.Sc. Microbiology and Biotechnology. The current presentation describes the dynamic interplay of thermodynamic principles in living systems and biochemistry.

1. Presented by
Dr. Ujwalkumar Trivedi, Ph.D., FICS
Head
Department of Biotechnology
Marwadi University
Rajkot (Gujarat)
Biochemistry: A Mere Game of
Thermodynamic Principles
Date: 25/04/2020
Quarantine Classes Course 3:
Fundamentals of Thermodynamics and its Implications in Biochemistry

2. Bioenergetics is a field in biochemistry and cell biology that
concerns energy flow through living systems. This is an active
area of biological research that includes the study of the
transformation of energy in living organisms and the study of
thousands of different cellular processes such as cellular
respiration and the many other metabolic and enzymatic
processes that lead to production and utilization of energy in
forms such as adenosine triphosphate (ATP) molecules. That is,
the goal of bioenergetics is to describe how living organisms
acquire and transform energy in order to perform biological
work.[4] The study of metabolic pathways is thus essential to
bioenergetics.

3. High ΔH and Low ΔS Low ΔH and High ΔS

4. Dissipative structures are open
systems, they need a continual input
of free energy from the environment
in order to maintain the capacity to
do ‘work’. It is this continual flux of
energy, into and out of a dissipative
structure, which leads towards self-
organization and ultimately the ability
to function at a state of non-
equilibrium.

5. (Just like the convection of water,
biological organisms are also self-
organizing dissipative structures, they
take in and give off energy from the
environment in order sustain life
processes and in doing so function at a
state of non-equilibrium. Although
biological organisms maintain a state far
from equilibrium they are still controlled
by the second law of thermodynamics.
Like all physiochemical systems,
biological systems are always increasing
their entropy or complexity due to the
overwhelming drive towards equilibrium.
But, unlike physiochemical systems,
biological systems possess ‘information’
that permits them to self-replicate and
continuously amplify their complexity
and organization through time.

6. If you take a thin layer of water, at uniform temperature, and start heating it from the bottom, a strange ordered
structure begins to appear. As the temperature between the bottom and top of the water reaches a critical level, the
water begins to move away from an equilibrium state and an instability within the system develops. At this point,
convection commences and the dissipative structure forms. As heat is transferred through the liquid, a patterned
hexagonal or ‘honey combed’ shape emerges (Bénard cells) and the capacity to do ‘work’ is realized (life). But, as
soon as the energy source (heat) is taken away, the ordered pattern disappears and the water returns to an
equilibrium state (death).

7. Although the chemical composition of an organism
may be almost constant through time, the population
of molecules within a cell or organism is far from
static. Molecules are synthesized and then broken
down by continuous chemical reactions, involving a
constant flux of mass and energy through the
system. The hemoglobin molecules carrying oxygen
from your lungs to your brain at this moment were
synthesized within the past month; by next month
they will have been degraded and replaced with new
molecules. The glucose you ingested with your most
recent meal is now circulating in your bloodstream;
before the day is over these particular glucose
molecules will have been converted into something
else, such as carbon dioxide or fat, and will have
been replaced with a fresh supply of glucose. The
amount of hemoglobin and glucose in the blood
remains nearly constant because the rate of synthesis
or intake of each just balances the rate of its
breakdown, consumption, or conversion into some
other product. The constancy of concentration does
not, therefore, reflect chemical inertness of the
components, but is rather the result of a dynamic
steady state.

8. Spontaneous Process
Non-spontaneous
Process
Equilibrium

9. The downward motion of an object releases potential energy that can do work. The potential energy made available
by spontaneous downward motion (an exergonic process, represented by the pink box) can be coupled to the
upward movement of another object (an endergonic process, represented by the blue box). A spontaneous
(exergonic) chemical reaction (B→C) releases free energy, which can pull or drive an endergonic reaction (A→B)
when the two reactions share a common intermediate, B. The exergonic reaction B→C has a large, negative free-
energy change (ΔGB→C), and the endergonic reaction A→B has a smaller, positive free-energy change (ΔGA→B). The
free-energy change for the overall reaction A→C is the arithmetic sum of these two values (ΔGA→C). Because the
value of ΔGA→C is negative, the overall reaction is exergonic and proceeds spontaneously.

11. Activation energy can be thought of as the magnitude of
the potential barrier (sometimes called the energy barrier)
separating minima of the potential energy surface
pertaining to the initial and final thermodynamic state. For
a chemical reaction, or division to proceed at a reasonable
rate, the temperature of the system should be high enough
such that there exists an appreciable number of molecules
with translational energy equal to or greater than the
activation energy.
A substance that modifies the transition state to lower the
activation energy is termed a catalyst; a catalyst composed
only of protein and (if applicable) small molecule cofactors
is termed an enzyme. A catalyst increases the rate of
reaction without being consumed in the reaction. In
addition, the catalyst lowers the activation energy, but it
does not change the energies of the original reactants or
products, and so does not change equilibrium. Rather, the
reactant energy and the product energy remain the same
and only the activation energy is altered (lowered).

14. Because the concentrations of the direct products of ATP hydrolysis are, in the cell, far below the
concentrations at equilibrium mass action favors the hydrolysis reaction in the cell.

17. Total: 686 kcal/mol
234 kcal/mol
trapped
Almost nothing
is trapped

18. Thank You
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