Biophysics

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Biophysicsis an interdisciplinary science that applies approaches and methods traditionally used inphysicsto studybiologicalphenomena.^[1][2][3]Biophysics covers all scales ofbiological organization, frommoleculartoorganismicandpopulations. Biophysical research shares significant overlap withbiochemistry,molecular biology,physical chemistry,physiology,nanotechnology,bioengineering,computational biology,biomechanics,developmental biologyandsystems biology.

The termbiophysicswas originally introduced byKarl Pearsonin 1892.^[4][5]The termbiophysicsis also regularly used in academia to indicate the study of thephysical quantities(e.g.electric current,temperature,stress,entropy) in biological systems. Otherbiological sciencesalso perform research on the biophysical properties of living organisms includingmolecular biology,cell biology,chemical biology, andbiochemistry.

Molecular biophysicstypically addresses biological questions similar to those inbiochemistryandmolecular biology, seeking to find the physical underpinnings of biomolecular phenomena. Scientists in this field conduct research concerned with understanding the interactions between the various systems of a cell, including the interactions betweenDNA,RNAandprotein biosynthesis, as well as how these interactions are regulated. A great variety of techniques are used to answer these questions.

Fluorescentimaging techniques, as well aselectron microscopy,x-ray crystallography,NMR spectroscopy,atomic force microscopy(AFM) andsmall-angle scattering(SAS) both withX-raysandneutrons(SAXS/SANS) are often used to visualize structures of biological significance.Protein dynamicscan be observed byneutron spin echospectroscopy.Conformational changein structure can be measured using techniques such asdual polarisation interferometry,circular dichroism,SAXSandSANS. Direct manipulation of molecules usingoptical tweezersorAFM, 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 entities which can be understood e.g. throughstatistical mechanics,thermodynamicsandchemical 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 individualmoleculesor complexes of molecules.

In addition to traditional (i.e. molecular and cellular) biophysical topics likestructural biologyorenzyme kinetics, modern biophysics encompasses an extraordinarily broad range of research, frombioelectronicstoquantum biologyinvolving both experimental and theoretical tools. It is becoming increasingly common for biophysicists to apply the models and experimental techniques derived fromphysics, as well asmathematicsandstatistics, to larger systems such astissues,organs,^[6]populations^[7]andecosystems. Biophysical models are used extensively in the study of electrical conduction in singleneurons, as well as neural circuit analysis in both tissue and whole brain.

Medical physics, a branch of biophysics, is any application ofphysicstomedicineorhealthcare, ranging fromradiologytomicroscopyandnanomedicine. For example, physicistRichard Feynmantheorized about the future ofnanomedicine. He wrote about the idea of amedicaluse forbiological machines(seenanomachines). Feynman andAlbert Hibbssuggested that certain repair machines might one day be reduced in size to the point that it would be possible to (as Feynman put it) "swallow the doctor". The idea was discussed in Feynman's 1959 essayThere's Plenty of Room at the Bottom.^[8]

The studies ofLuigi Galvani(1737–1798) laid groundwork for the later field of biophysics. Some of the earlier studies in biophysics were conducted in the 1840s by a group known as the Berlin school of physiologists. Among its members were pioneers such asHermann von Helmholtz,Ernst Heinrich Weber,Carl F. W. Ludwig, andJohannes Peter Müller.^[9]

William T. Bovie(1882–1958) is credited as a leader of the field's further development in the mid-20th century. He was a leader in developingelectrosurgery.

The popularity of the field rose when the bookWhat Is Life?byErwin Schrödingerwas published. Since 1957, biophysicists have organized themselves into theBiophysical Societywhich now has about 9,000 members over the world.^[10]

Some authors such asRobert Rosencriticize biophysics on the ground that the biophysical method does not take into account the specificity of biological phenomena.^[11]

While some colleges and universities have dedicated departments of biophysics, usually at the graduate level, many do not have university-level biophysics departments, instead having groups in related departments such asbiochemistry,cell biology,chemistry,computer science,engineering,mathematics,medicine,molecular biology,neuroscience,pharmacology,physics, andphysiology. Depending on the strengths of a department at a university differing emphasis will be given to fields of biophysics. 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.^{[citation needed]}

• Biologyandmolecular biology–Gene regulation, singleprotein dynamics,bioenergetics,patch clamping,biomechanics,virophysics.
• Structural biology– Ångstrom-resolution structures of proteins, nucleic acids, lipids, carbohydrates, and complexes thereof.
• Biochemistryandchemistry– biomolecular structure, siRNA, nucleic acid structure, structure-activity relationships.
• Computer science–Neural networks, biomolecular and drug databases.
• Computational chemistry–molecular dynamicssimulation,molecular docking,quantum chemistry
• Bioinformatics–sequence alignment,structural alignment,protein structure prediction
• Mathematics– graph/network theory, population modeling, dynamical systems,phylogenetics.
• Medicine– biophysical research that emphasizes medicine. Medical biophysics is a field closely related to physiology. It explains various aspects and systems of the body from a physical and mathematical perspective. Examples arefluid dynamicsof blood flow, gas physics of respiration, radiation in diagnostics/treatment and much more. Biophysics is taught as a preclinical subject in manymedical schools, mainly in Europe.
• Neuroscience– studying neural networks experimentally (brain slicing) as well as theoretically (computer models), membranepermittivity.
• Pharmacologyandphysiology–channelomics,electrophysiology, biomolecular interactions, cellular membranes,polyketides.
• Physics–negentropy,stochastic processes, and the development of new physicaltechniquesandinstrumentationas well as their application.
• Quantum biology– The field of quantum biology appliesquantum mechanicsto biological objects and problems.Decoheredisomersto yield time-dependent base substitutions. These studies imply applications in quantum computing.
• Agronomyandagriculture

Manybiophysical techniquesare unique to this field. Research efforts in biophysics are often initiated by scientists who were biologists, chemists or physicists by training.

• Biophysical Society
• Journal of Physiology: 2012 virtual issueBiophysics and Beyond
• bio-physics-wiki
• Link archive of learning resources for students:biophysika.de(60% English, 40% German)