Biophysics

1
Biophysics

• Introduction to biophysics
• Course Plan
• Course Contents
• Reference Books

2
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

3
Course Plan

• Quiz/Assignments 10 marks
• Sessionals 202040 marks
• Terminal 50 marks

4
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

5
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

6
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

7

• 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

8
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

9
Osmosis in fresh and sea water fish
Fresh water trout
Sea water Herring
10
Turgid plant
wilting
The cells have taken up water by osmosis the
cells are turgid and the tissue is firm
These cells are short of water the tissue is
limp and the plant is wilting
11
Growth in a shoot tip
25
cell division continues
these cells will divide
vacuoles forming
cells absorb water by osmosis and expand
12
Effect of different solutions on blood cells
13
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

14
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.