Biophysics

The biophysics is a discipline with the interface of the Physique and the Biologie where the tools of observations of the physical phenomena are applied to the molecules of biological interest.

Several fields of biology in its broadest direction profited from the projections carried out by biophysics. Let us quote simply the Médecine, the cellular Biologie or the Molecular biology.

An approach inherited physics is used there for:

  • to carry out internal images of organization: IRM, Radiography or to treat cancerous tumors: Radiotherapy
  • to highlight the structure of components of the alive one: DNA or the Protein S
  • to measure and handle more and more precisely the components of the alive one. As example, it is possible to use optical grips to move Organite S or to unroll the double helix of the DNA by measuring the force applied.

These forty last years, biophysics underwent a change which led to an increasingly molecular approach, i.e. reductionistic, biological phenomena.

Short history

The physiologists, who were the first biophysicists, showed later that only the laws of physics are necessary and sufficient to explain all living it. Recently, since nobody any more called upon the theory of the Vitalisme, this discipline transferred and took for goal the characterization of the molecules of alive by means of physical and chemical techniques.

Theoretical aspect

The Physique intends to explain the biological phenomena by the same laws which apply to the rest of the world. It is in that the direct heiress of the Physiologie of the beginning of the 20th century. As for much of other systems having an private interest (Liquid S, plasmas, superconductive…), the biophysicists seek to develop theories adapted to the typical phenomena of the alive world. In many cases, such theories highlight certain common points between observations a priori very different, and open new prospects. It is that the living organisms belong to the physical systems most complex and most varied which are accessible to our observation. However there exists a remarkable unit at the cellular level, already highlighted by the first observations of cell S at the microscope (Schleiden 1838, Schwann 1839, Virchow 1855).

The progressive discovery of the unit of the physical processes intervening in all the alive cells was an important engine for the development of biophysics. The physicists indeed seek to explain the main part of the observations by proposing synthetic theories. The most important successes are obtained when several observations in different contexts, at different organization S, are attached to the same physical explanation.

Specialized articles:

Particularly important fields of the theoretical physics in biophysics:

  • Physical statistics out of Dynamic balance
  • of the fluids
  • Physical Rheology
  • of the polymers
  • Structure of the Physical matter
  • Spectroscopy and electrostatic Radiation
  • , Magnetism

Experimental aspect

Techniques of observation developed primarily thanks to progress in physics:

  • NMR, nuclear Magnetic resonance, which makes it possible to solve the three-dimensional structure of small molecules,

  • IRM, Imagerie by magnetic resonance,
  • the X-rays used in Cristallographie, which make it possible to solve the structure of molecules of any size, in the condition which they form of the regular crystals,
    • used in Diffractométrie on a Diffractomètre
    • composed of a Goniomètre and a camera CCC
  • RPE, electronic paramagnetic resonance ,
  • SPR, surface plasmon resonance ,
  • the Spectrometry mass, which makes it possible to identify proteins,
  • the electrophysiology, which measures the electric activity of the cells,
  • the Biophotonique and the microscopy of fluorescence,
  • the Microcalorimétrie, which measures the changes of heat during a reaction, for example the connection of molecules of water to a protein,
  • the Microtensométrie, which makes it possible to measure the forces of interaction within double-layered lipidic,
  • the Chain reaction by polymerase ( polymerase chain reaction or PCR), whose applications in the field of the handling of the DNA are innumerable.

All this requires the handling and the purification of these molecules while using the liquid Chromatography with high pressure or in English HPLC, the electrophoresis, the Crystallogenesis, the Cytométrie in flow, the genetic Engineering and of the techniques allowing to obtain in sufficient quantity of the identical molecules, such as the Chain reaction by polymerase.

The equipment is not yet able “to see” a molecule but in “illuminant” a great number of identical molecules with a controlled radiation, x-rays with the radio waves (NMR, RPE), it is possible to deduce from it their common structure by the analysis of the re-emitted radiation. To note that electrophysiology makes it possible to follow the activity in real-time of only one molecule thanks to the technique of patch clamp. This requires the handling of a very great number of measurements.

The use of a fundamental ideal model containing Quantum physics and thus the use of the computer tools essential and are often connected to the Internet.

The re-emitted radiation is also used to locate these Molécule S in space; it is what is used in imagery. That often implies the coupling of the molecule of interest to a fluorophore Biophotonique.

The examples of use of these techniques in medicine are innumerable. One will be able to retain, for example, the genome decoded, Sida and protein TAT, use of the RPE. A discipline uses these various tools and techniques in order to apply them to medicine: Génomique structural

See too

External bonds

  • http://www.dnaftb.org/dnaftb/41/concept/
  • http://molvis.sdsc.edu/visres/
  • http://biophysique.univ-lyon1.fr

Simple: Biophysics

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