You use an electron microscope to view living cells for a few specific reasons, but it's important to clarify that you generally cannot view living cells with a traditional electron microscope.

Here's why:

* Sample Preparation: Electron microscopy requires extremely thin samples, often less than 100 nanometers thick. This preparation process, which involves dehydration, fixation, and embedding, is fatal to living cells.

* Vacuum Environment: Electron microscopes operate under a high vacuum to prevent the electron beam from scattering. This environment would instantly kill living cells.

However, there are specialized techniques that allow us to view biological processes in near-living conditions:

* Cryo-electron microscopy (cryo-EM): This technique rapidly freezes samples, preserving their structure in a near-native state. It's revolutionized our understanding of biological molecules and has been used to image viruses, proteins, and even entire cells at high resolution.

* Environmental Scanning Electron Microscopy (ESEM): This technique allows imaging of samples in a low-pressure, humidified environment, making it possible to observe some aspects of biological activity, including the growth of bacteria.

Why use electron microscopes at all for biological research?

* High Resolution: Electron microscopes provide much higher resolution than light microscopes, allowing us to see structures as small as individual atoms.

* Detailed Morphology: We can study the internal structures of cells, including organelles, membranes, and protein complexes, in great detail.

In summary:

While traditional electron microscopy is not suitable for viewing living cells, specialized techniques like cryo-EM and ESEM offer valuable insights into the structure and dynamics of biological systems.