Biophysics (also biological physics) is an interdisciplinary science that applies theories and methods of the physical sciences to questions of biology. Biophysics research today comprises a number of specific biological studies, which do not share a unique identifying factor, or subject themselves to clear and concise definitions. This is the result of biophysics' relatively recent appearance as a scientific discipline. The studies included under the umbrella of biophysics range from sequence comparison to neural networks. In the recent past, biophysics included creating mechanical limbs and nanomachines to regulate biological functions. Nowadays, these are more commonly referred to as belonging to the fields of bioengineering and nanotechnology respectively. We may expect these definitions to further refine themselves.

Overview

Traditional studies in biology are conducted using statistical ensemble experiments, using molar concentrations of macromolecules. Because the molecules that comprise living cells are so small, techniques such as PCR amplification, gel blotting, fluorescence labeling and in vivo staining are used so that experimental results are observable with an unaided eye or, at most, optical magnification. Using these techniques, biologists attempt to elucidate the complex systems of interactions that give rise to the processes that make life possible. Biophysics typically addresses biological questions similar to those in biology, but the questions are asked at a molecular (i.e. low Reynolds number) level. By drawing knowledge and experimental techniques from a wide variety of disciplines (as described below), biophysicists are able to indirectly observe or model the structures and interactions of individual molecules or complexes of molecules. In addition things like solving a protein structure or measuring the kinetics of single molecule interactions, biophysics is also understood to encompass research areas that apply models and experimental techniques derived from physics (e.g. electromagnetism and quantum mechanics) to larger systems such as tissues or organs (hence the inclusion of basic neuroscience as well as more applied techniques such as fMRI).

Biophysics often does not have university_level departments of its own, but have presence as groups across departments within the fields of biology, biochemistry, chemistry, computer science, mathematics, medicine, pharmacology, physiology, physics, and neuroscience. What follows is a list of examples of how each department applies its efforts toward the study of biophysics. This list is hardly all inclusive. Nor does each subject of study belong exclusively to any particular department. Each academic institution makes its own rules and there is much mixing between departments.

• Biology and molecular biology - Almost all biophysics efforts are included in some biology department somewhere. To include some: gene regulation, single protein dynamics, bioenergetics, patch clamping, phylogenetic tree.
• Structural Biology - angstrom-resolution structures of proteins, nucleic acids, lipids, carbohydrates, and complexes thereof.
• Biochemistry and chemistry _ biomolecular structure, siRNA, nucleic acid structure, structure_activity relationships.
• Computer science - molecular simulations, sequence alignment, neural networks, databases.
• Mathematics - graph/network theory, population modeling, (also provides a foundation for physics).
• Medicine and neuroscience - tackling neural networks experimentally (brain slicing) as well as theoretically (computer models), membrane permitivity, gene therapy, understanding tumors.
• Pharmacology and physiology _ channel biology, biomolecular interactions, cellular membranes, polyketides.
• Physics - biomolecular free energy, biomolecular structures and dynamics, protein folding, stochastic processes, surface dynamics.

Many biophysical techniques are unique to this field. Many of the research traditions in biophysics were initiated by scientists who were straight physicists, chemists, and biologists by training.

Topics in biophysics and related fields

• animal locomotion
• cellular biophysics
• channels, receptors and transporters
• electrophysiology
• membranes
• bioenergetics
• muscle and contractility
• nucleic acids
• photobiophysics and biophotonics
• proteins
• supramolecular assemblies
• spectroscopy, imaging etc.
• systems neuroscience
• neural encoding
• bionics
• polysulphur membranes

Famous biophysicists

• Luigi Galvani, discoverer of bioelectricity
• Hermann von Helmholtz, first to measure the velocity of nerve impulses
• Alan Hodgkin & Andrew Huxley, created modern understanding of nerve impulses
• Georg von Békésy, research on the human ear
• Bernard Katz, discovered how synapses work
• Maurice Wilkins & Rosalind Franklin, pioneers of DNA crystallography
• Francis Crick, co-discover of DNA structure and the genetic code
• Max Perutz & John Kendrew, pioneers of protein crystallography

Other notable biophysicists

• Friedrich Dessauer, research on radiation, especially X-rays
• Walter Friedrich
• Boris Rajewsky
• Mikhail Volkenshtein, Revaz Dogonadze & Zurab Urushadze, authors of the Quantum-Mechanical (Physical) Model of Enzyme Catalysis

References

• Perutz M.F. Proteins and Nucleic Acids, Elsevier, Amsterdam, 1962
• Perutz M.F. The haemoglobin molecule.- Proc.Roy.Soc., B 173, 1969, pp. 113-140
• Dogonadze R.R. and Urushadze Z.D. Semi-Classical Method of Calculation of Rates of Chemical Reactions Proceeding in Polar Liquids.- J.Electroanal.Chem., 32, 1971, pp. 235-245
• Volkenshtein M.V., Dogonadze R.R., Madumarov A.K., Urushadze Z.D. and Kharkats Yu.I. Theory of Enzyme Catalysis.- Molekuliarnaya Biologia (Moscow), 6, 1972, pp. 431-439 (In Russian, English summary)

See also

• Important publications in biophysics (biology), important publications in biophysics (physics)

External links

• Biophysical Society (http://www.biophysics.org/)
• Biophysics Textbook Online (http://www.biophysics.org/btol/)
• Previous link seems broken, try this one (http://web.archive.org/web/20030621141020/www.biophysics.org/btol/)