Cells are the smallest structures capable of basic life processes, such as taking in nutrients, expelling waste, and reproducing. All living things are composed of cells. Some microscopic organisms, such as bacteria and protozoa, are unicellular, meaning they consist of a single cell. Plants, animals, and fungi are multicellular, meaning they are composed of a great many cells working all together. But whether it makes up an entire bacterium or is just one of trillions …showed first 75 words of 509 total…

…showed last 75 words of 509 total…smaller than a wavelength of visible light - about 0.2 microns -Nor can they allow scientists to examine individual tiny parts of cells in detail . To view extremely tiny objects, scientists use electron microscopes . Electron microscopes use streams of electrons instead of light to create images. Scientists don't see the images directly through lenses as they do with light microscopes . Instead, the machinery of the electron microscope generates a picture on a TV or computer screen .