Biophysical Chemistry

Syllabus:

1. Thermodynamics: System, state and state functions, conservation of energy First law of thermodynamics: Introduction, definitions, nature of heat and work, PV work, maximum work, first law of thermodynamics - internal energy enthalpy, molar heat capacities, isothermal and adiabatic expansion, reversible and irreversible processes, The first law to biological systems, enthalpy and heal capacities of reactions of biochemical interest; enthalpy and heat capacities of proteins; protein stability, enthalpy of ligand-protein and ligand-membrane interaction.

2. Thermochemistry: Exothermic and endothermic reactions, standard enthalpy of formation, thermochemical equations, reaction enthalpy - dependence on temperature, bond energy. Second law of thermodynamics: Thermodynamics-reversibility and irreversibility, spontaneous processes, entropy, thermodynamic efficiency and Carnot's theorem, statements of second law, entropy changes - phase transition, heating, irreversible processes, Third law of thermodynamics, Free variation with temperature and pressure, Gibbs-Helmholtz energy - equation, applications of thermodynamics in biochemistry, biochemical relevance of classical thermodynamics, thermodynamic reactions in aqueous solution. Enthalpy and its temperature dependence. Applications of thermodynamics.

3. Properties of Liquid and Solutions: Viscosity, surface tension, Vapor pressure, Roult's law, Henry's law and their application in biology, effect of temperature and pressure on solution properties during respiration and photosynthesis, solutions of non-electrolyte in human, electrolytes in biological system (solutions, ionizations, activity coefficient and ionic strength), the electric potential of cellular membranes, Donnan effect and the erythrocyte function, active and passive transport. 

4. Acids, Bases and Buffers: Definitions, strength and neutralization reactions of acids and bases, acids and bases of GIT, pH and its biochemical relevance, buffer solutions and buffer capacity, physiological buffers (buffer of blood, plasma) etc. 

5. Chemical Equilibrium: Nature of chemical equilibrium, equilibrium and semipermeable membrane of cell, equilibrium constant, relationship to free energy, effect of temperature on cellular equilibrium, reaction involving hydrogen ion in buffer media, coupling of reactions inside cells, kinetics of biochemical reactions and its applications in Biochemistry. 

6. Chemical kinetics: Definition, reaction rate, rate laws, zero-, first- and second- order reactions, molecularity of a reaction, pseudo-first order reaction, half-life, determination of order and rate constant, effect of temperature on reaction rates. Theories of reaction rates the collision theory, the activated complex theory Catalysis - definition, types, characteristics of catalysts, activation energy and catalysis.  

7. Photometry: Beer-Lambert law, standard curve, application in Biochemistry.

8. Electrochemistry: Oxidation-reduction reaction, electromotive force, electrodes and electrode potentials, electrochemical cells. Thermodynamics of electrochemical cells, relationship between standard emf and equilibrium constant, Nernst equation, temperature dependence of emf, applications of emf.

Book: 

1. Essential of Physical Chemistry, Bahl & Tuli 


LECTURE NOTES ON THERMODYNAMICS, Joseph M. Powers

Chapter 1 (Thermodynamics) & Chapter 2 (Thermochemistry):

Thermodynamics

Zeroth Law of Thermodynamics

  • The Zeroth law of thermodynamics states that if two bodies are individually in equilibrium with a separate third body, then the first two bodies are also in thermal equilibrium with each other.
  • This means that if system A is in thermal equilibrium with system C and system B is also in equilibrium with system C, then system A and B are also in thermal equilibrium.
Two cups measuring 100 °C are in equilibrium with each other

First Law of Thermodynamics


  • Relation between heat and work and the concept of internal energy

  • Energy is always conservedi.e., it can neither be created nor destroyed, but it can be transformed from one form to another
  • Internal energy is a thermodynamic property of the system that refers to the energy associated with the molecules of the system, which includes kinetic energy and potential energy.

First Law of Thermodynamics in Biological Systems

All biological organisms require energy to survive. In a closed system, such as the universe, this energy is not consumed but transformed from one form to another. 

Cells, for example, perform a number of important processes. These processes require energy. 

In photosynthesis, the energy is supplied by the sun. Light energy is absorbed by cells in plant leaves and converted to chemical energy. The chemical energy is stored in the form of glucose, which is used to form complex carbohydrates necessary to build plant mass.

The energy stored in glucose can also be released through cellular respiration. This process allows plant and animal organisms to access the energy stored in carbohydrates, lipids, and other macromolecules through the production of ATP. This energy is needed to perform cell functions such as DNA replication, mitosis, meiosis, cell movement, endocytosis, exocytosis, and apoptosis.


Why “∆G = ∆H – T∆S” is the most important equation in biochemistry?


  • Biochemistry is the study of biologically relevant chemical reactions, mainly those involving carbon-containing molecules. 

    "∆G = ∆H - T∆S" is the most important equation in biochemistry because it reveals that spontaneous chemical reactions — those that occur all by themselves without external intervention — must release free energy (∆G). 

    Cells use the free energy released by spontaneous chemical reactions to drive non-spontaneous chemical reactions, which require an input of free energy. If cells could not "couple" reactions in this way, life itself would not be possible.

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