Thermodynamics in biophysics

1. Biophysics
Dr. Qamar Yasmeen (PhD, Biochemistry)

2. Bioenergetics
• Bioenergetics is the branch of biochemistry that focuses on how cells
transform energy, often by producing, storing or consuming
adenosine triphosphate (ATP).

4. Essentials of Thermodynamics
• Thermodynamics is the study of the relationship between heat, work,
and the associated flow of energy
• Thermodynamics is concerned with storage, transformation and
dissipation of energy
• Cell store energy, they transform it into another form then it is
converted to heat to perform unfavorable reactions in the living
system

6. Thermodynamics objectives
• All biological, chemical and physical processes are regulated and
enabled by laws of thermodynamics
• Relationship between heat and work in living/biological system
• Changes in energy forms in biological reactions
• For understanding of biochemical reaction taking place in biological
systems
• For measurement of effect of temperature on physico-chemical and
biological reactions

7. Thermodynamics concept considering a
biological approach
• Heat produced by humans/animals is due to the slow combustion of food in their bodies.
• The body of an animal/humans contains internal thermal energy Et, which
is the product of the mass and specific heat, and chemical energy Ec stored
in the tissue of the body
• The energy released by the food is balanced by the lost body heat and the
work done by the body.

8. Thermodynamic changes are essential for
biochemical function and metabolism i.e.
anabolism and catabolism

9. Thermodynamic concepts are used to explain:
• The direction of chemical reactions
• The speed of the chemical reactions e.g. enzymatic reactions
• The concentration conditions of the equilibrium state
• The maximum work performed through a chemical transformation
• How the cell can operate and are able to produce their characteristic
compounds and maintain their metabolic processes

10. System

11. Types of system
• Isolated-No exchange of energy or matter.
• Example: A thermos is an attempt to isolate a
system. An ice chest is another example of an
attempt to isolate a system
• Closed: Only energy allowed to exchange.
• Examples: A chicken’s egg, Unopened can of
soda. Stoppered reaction flask
• Open: Both energy and matter allowed to
exchange.
• Examples: Humans, Cell, Open reaction flask.
Opened can of soda

12. Laws of thermodynamics
• The laws of thermodynamics are important unifying principles
of biology. These principles govern the chemical processes
(metabolism) in all biological organisms.
• The First Law of Thermodynamics, also known ​as the law of
conservation of energy, states that energy can neither be created nor
destroyed. It may change from one form to another, but the energy in
a closed system remains constant

13. 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.

14. • 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.