what is the raw experimental data of cryo-electron microscopy cryo-EM

The raw experimental data of cryo-electron microscopy (cryo-EM) typically consists of a series of images or micrographs of the sample being studied. These images are captured using an electron microscope, which directs a beam of electrons onto the sample and records the resulting interactions.

In cryo-EM, the sample is flash-frozen in a thin layer of vitreous ice to preserve its native structure. The images obtained are two-dimensional projections of the sample at different orientations. To obtain a three-dimensional structure, multiple images are collected from different angles.

The raw data can be in the form of digital images, often stored in a specific file format such as MRC (Medical Research Council) or TIFF (Tagged Image File Format). Each image represents a projection of the sample at a specific orientation.

The raw data also includes metadata such as microscope parameters, exposure time, pixel size, and defocus values. This information is crucial for subsequent image processing and reconstruction steps to generate a high-resolution three-dimensional structure of the sample.

It's important to note that the raw data alone is not sufficient to determine the structure of the sample. Extensive image processing and computational analysis are required to align and combine the images, correct for artifacts, and reconstruct the three-dimensional structure using techniques such as Fourier transformation and iterative algorithms.