Download Biophysics

Introduction to biophysics
Course Plan
Course Contents
Reference Books
What is “Biophysics”
Biophysics is a specialized sub area of biology
It is the science of physical principles of life itself and of
biological systems. Biophysics is an interdisciplinary
science that explains the laws and principles of physics
which govern various biological processes. Biophysics
spans all levels of biological organization from molecular
scale to whole organism
Course Plan
 Quiz/Assignments: 10 marks
 Sessionals: 20+20=40 marks
 Terminal: 50 marks
Course Contents
 Introduction to biophysics
 Basic concepts
Osmosis, osmotic pressure, surface tension, diffusion, viscosity,
thermal conduction, forces and energy
 Molecular structure of biological systems at a glance
 Energetics and Dynamics of Biological Systems
Description of ATP, cell as an accumulator of electrochemical energy,
energy consumption, respiration, mechanism of molecular energy
transfer, thermodynamics and thermal molecular movement,
mechanism of body temperature regulation, photosynthesis as a
process of energy transfer and transformation, dynamics of blood flow,
control of movement
Course Contents
 Biological Membranes
Membrane chemistry and structure, membrane physics, surface and
interfacial tensions, diffusion and mobility of ions, electrostatic and
mechanical properties of membranes
 Mechanical Properties of Biological Materials
fluid flow, blood circulation, muscle contraction, swimming, flying etc
 Electric fields in cells and organisms
Nerve Signals, nerve impulses, nervous system
 Physical factors of the environment
Temperature, pressure, mechanical oscillations (vibrations, sound,
hearing and hearing aids, effect of ultrasound), electromagnetic fields
in the environment, ionizing radiations
ebooks
 Textbook:
Biophysics by P. S. Mishra, 2010
 Reference books:
 Molecular And Cellular Biophysics by Meyer B.
Jackson, Cambridge University Press, 2006
 Biophysics by Roland Glaser, Springer, 2001
 An Introduction to Med. Biophysics by Parveen
Parkash
 Biological activities happening in different organs of
living body like kidney, liver, heart, lungs as well as
those in intracellular and extracellular biological fluid
are governed by fundamental laws of physics namely
 Diffusion
 Osmosis
 Viscosity
 Surface Tension
Osmosis
 The spontaneous passage of solvent from a solution of lower
concentration towards a solution of higher concentration when the
two are separated by a semi permeable membrane is called osmosis
 Osmosis is a special case of diffusion. It involves the diffusion of water
through the semi permeable membrane to equalise the concentration
of solutions on its two sides
Osmosis in fresh and sea water
fish
Fresh water trout
Sea water Herring
wilting
These cells are short of water; the
tissue is limp and the plant is wilting
Turgid plant
The cells have taken up water by
osmosis; the cells are turgid and the
tissue is firm
25
Growth in a shoot tip
these cells will divide
cell division
continues
vacuoles
forming
cells absorb
water by
osmosis and
expand
Effect of different solutions on
blood cells
Osmosis
 Osmosis releases energy, and can be made to do work, as




when a growing tree root splits a stone.
Diffusion and Osmosis are both types of PASSIVE
TRANSPORT - that is, no energy is required for the
molecules to move into or out of the cell.
Osmosis takes place due to difference in chemical
potentials of water on two sides of membranes
which
leads to pressure gradient
Solute decreases chemical potential of water. Water tends
to flow from where its chemical potential is higher to
where it is lower
Reduced chemical potential causes reduced vapor pressure,
lower freezing point and higher boiling point of the
solution as compared with pure water
Osmotic Pressure
 Osmosis may be opposed by increasing the pressure in the
region of high solute concentration (hypertonic solution)
with respect to that in the low solute concentration region
(hypotonic solution).
 The hydrostatic pressure which just stops osmosis is the
osmotic pressure
 The force per unit area, or pressure, required to prevent the
passage of water through a selectively-permeable
membrane and into a solution of greater concentration is
equivalent to the osmotic pressure of the solution, or
turgor.
 Osmotic pressure is a colligative property, meaning that the
property depends on the concentration of the solute but
not on its identity.