Biophysics

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Biophysics

Biophysics (also biological physics) is an interdisciplinary science that applies the theories and methods of physical sciences, especially those of physics, 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, typically using pico- to micro-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 to 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 forms of biophysics efforts are included in some biology department somewhere. To include some: gene regulation, single protein dynamics, bioenergetics, patch clamping, biomechanics.
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, dynamical systems, phylogenetical analysis.
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

Famous biophysicists

Luigi Galvani, discoverer of bioelectricity
Hermann von Helmholtz, first to measure the velocity of nerve impulses; studied hearing and vision
Alan Hodgkin & Andrew Huxley, mathematical theory of how ion fluxes produce nerve impulses
Georg von Békésy, research on the human ear
Bernard Katz, discovered how synapses work
Hermann J. Muller, discovered that X-rays cause mutations
Linus Pauling & Robert Corey, co-discoverers of the alpha helix and beta sheet structures in proteins
Fritz-Albert Popp, pioneer of biophotons work
J. D. Bernal, X-ray crystallography of plant viruses and proteins
Rosalind Franklin, Maurice Wilkins, James D. Watson and Francis Crick, pioneers of DNA crystallography and co-discoverers of the genetic code
Max Perutz & John Kendrew, pioneers of protein crystallography
Allan Cormack & Godfrey Hounsfield, development of computer assisted tomography
Paul Lauterbur & Peter Mansfield, development of magnetic resonance imaging

Other notable biophysicists

Adolf Eugen Fick, responsible for Fick's law of diffusion and a method to determine cardiac output.
Howard Berg, characterized properties of bacterial chemotaxis
Steven Block, observed the motions of enzymes such as kinesin and RNA polymerase with optical tweezers
Carlos Bustamante, known for single-molecule biophysics of molecular motors and biological polymer physics
Steven Chu, Nobel Laureate who helped develop optical trapping techniques used by many biophysicists
Friedrich Dessauer, research on radiation, especially X-rays
Julio Fernandez
John J. Hopfield, worked on error correction in Transcription and Translation (kinetic proof-reading), and associative memory models (Hopfield net)
Franklin Offner, professor emeritus at Northwestern University of professor of biophysics, biomedical engineering and electronics who developed a modern prototype of the electroencephalograph and electrocardiograph called the dynograph
Benoit Roux
Mikhail Volkenshtein, Revaz Dogonadze & Zurab Urushadze, authors of the 1st Quantum-Mechanical (Physical) Model of Enzyme Catalysis, supported a theory that enzyme catalysis use quantum-mechanical effects such as tunneling.
John P. Wikswo, research on biomagnetism
Douglas Warrick, specializing in bird flight (hummingbirds and pigeons)
Balaji V N, specialized in computational biology

References

Perutz M.F. Proteins and Nucleic Acids, Elsevier, Amsterdam, 1962
PMID 4389425
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)

External links

Biophysical Society