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, 
agrophysics 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, NMR spectroscopy and 
atomic force microscopy (AFM) are often used to visualize 
structures of biological significance. Conformational 
changes in structure can be measured using techniques such 
as dual polarisation interferometry and circular dichroism. 
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 and cellular) 
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.

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