biophysics n : physics as applied to biological problems
Biophysics (also biological physics) is an interdisciplinary science that employs and develops theories and methods of the physical sciences for the investigation of biological systems. Studies included under the umbrella of biophysics span all levels of biological organization, from the molecular scale to whole organisms and ecosystems. Biophysical research shares significant overlap with biochemistry, nanotechnology, bioengineering and systems biology.
Molecular biophysics typically addresses biological questions that are similar to those in biochemistry and molecular biology, but the questions are approached quantitatively. Scientists in this field conduct research concerned with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis, as well as how these interactions are regulated. A great variety of techniques are used to answer these questions.
Fluorescent imaging techniques, as well as electron microscopy, x-ray crystallography and atomic force microscopy (AFM) are often used to visualize structures of biological significance. Direct manipulation of molecules using optical tweezers or AFM can also be used to monitor biological events where forces and distances are at the nanoscale. Molecular biophysicists often consider complex biological events as systems of interacting units which can be understood through statistical mechanics, thermodynamics and chemical kinetics. By drawing knowledge and experimental techniques from a wide variety of disciplines, biophysicists are often able to directly observe, model or even manipulate the structures and interactions of individual molecules or complexes of molecules.
In addition to traditional (i.e. molecular) biophysical topics like structural biology or enzyme kinetics, modern biophysics encompasses an extraordinarily broad range of research. It is becoming increasingly common for biophysicists to apply the models and experimental techniques derived from physics, as well as mathematics and statistics, to larger systems such as tissues, organs, populations and ecosystems.
Focus as a subfield
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 overlap 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 - Neural networks, Biomolecular and drug databases.
- Computational chemistry - Molecular dynamics simulation, Molecular docking, Quantum chemistry
- Bioinformatics - sequence alignment, structural alignment, Protein structure prediction
- Mathematics - graph/network theory, population modeling, dynamical systems, phylogenetics.
- 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, stochastic processes, covering dynamics.
Many biophysical techniques are unique to this field. Research efforts in biophysics are often initiated by scientists who were traditional physicists, chemists, and biologists by training.
Topics in biophysics and related fields
- Animal locomotion
- Biochemical systems theory
- Biological membranes
- Biosensor and Bioelectronics
- Cell division
- Cell membranes
- Cell migration
- Cell signalling
- Channels, receptors and transporters
- Dynamical systems
- Enzyme kinetics
- Evolutionarily stable strategy
- Evolutionary algorithms
- Evolutionary computing
- Evolutionary theory
- Game theory
- Gravitational biology
- Mathematical biology
- Metabolic control analysis
- Molecular biophysics
- Molecular motors
- Muscle and contractility
- Neural encoding
- Nucleic acids
- Origin of Life
- Photobiophysics and biophotonics
- Polysulphur membranes
- Punctuated equilibrium
- Sensory systems
- Spectroscopy, imaging, etc.
- Supramolecular assemblies
- Systems biology
- Systems neuroscience
- Theoretical biology
- 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
- 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 structure of DNA. Francis Crick later participated in the Crick, Brenner et al. experiment which established the basis for understanding 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
- Seiji Ogawa, development of functional 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
- Stefan Hell, developed the principle of STED microscopy
- John J. Hopfield, worked on error correction in Transcription and Translation (kinetic proof-reading), and associative memory models (Hopfield net)
- Martin Karplus, research on molecular dynamical simulations of biological macromolecules.
- 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)
- Ernest C. Pollard — founder of the Biophysical Society
- Marvin Makinen, pioneer of the structural basis of enzyme action
- Gopalasamudram Narayana Iyer Ramachandran, developer of the Ramachandran plot and pioneer of the collagen triple-helix structure prediction
- Doug Barrick, repeat protein folding and the Mechanisms underlying Notch Signaling
- Naomi Courtemanche, kinetics of Leucine Rich Repeat protein folding
- 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)
- Sneppen K. and Zocchi G., Physics in Molecular Biology, Cambridge University Press, 2005. ISBN 0-521-84419-3
- Glaser R., Biophysics, Springer, 2001, ISBN 3-540-67088-2
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