Biophysical methods in biology involve the use of physical and chemical principles to study biological systems at the molecular and cellular level. These methods are essential for understanding the structure, function, and interactions of biomolecules and biological systems. Here are some of the commonly used biophysical methods in biology:

1. X-ray crystallography: This method is used to determine the 3D structure of proteins and other biomolecules. It involves growing crystals of the biomolecule and exposing them to X-rays. The pattern of diffracted X-rays is used to determine the position of atoms in the molecule.

2. Nuclear magnetic resonance (NMR) spectroscopy: This technique is used to study the structure and dynamics of biomolecules in solution. It involves applying a magnetic field to the sample and measuring the response of the nuclei to the field.

3. Electron microscopy: This method uses a beam of electrons to visualize the structure of biological molecules and complexes at high resolution. It is particularly useful for studying large macromolecular complexes.

4. Mass spectrometry: This technique is used to determine the mass of biomolecules and to identify their chemical composition. It involves ionizing the sample and separating the ions based on their mass-to-charge ratio.

5. Fluorescence spectroscopy: This method is used to study the structure and function of biomolecules by measuring the emission of light from fluorescent probes attached to the molecule of interest.

6. Circular dichroism spectroscopy: This technique measures the differential absorption of left- and right-handed circularly polarized light by chiral molecules like proteins and nucleic acids. It is used to study protein folding and conformational changes.

These biophysical methods are critical for advancing our understanding of biological processes and developing new therapies for diseases. By combining these methods with computational and biochemical approaches, researchers can gain a comprehensive understanding of the complex biological systems.