A level biology questionWatch this thread
The diagram showing DNA shows the DNA being bombarded by a beam of X Rays, not electrons. The X rays are generated inside the X Ray tube by smashing electrons into an anode resulting in them releasing X Rays.
The X Rays will pass through the parts of the DNA not occupied by atoms such as the spaces between base pairs. This is Diffraction.
With electron microscopy it’s a beam of electrons that bombard the sample there are two types transmission and scanning.
With transmission the sample is sectioned and bombarded by electrons (e-) dense parts of the sample for example a cell or tissue let fewer e- through and thst gives an shadow on the photographic plate or detector showing the image of the cells.
With scanning electron microscopy samples eg. insects, cells, or even viruses are stained in a dense material such as gold. The e- bombard the sample and are reflected and an image is developed by the detector.
You’d probably get a better answer in the chemistry or physics section
Hope that helps