* Size: Mitochondria are very small organelles, typically measuring a few micrometers in length. Light microscopes lack the resolution to visualize such small structures.

* Internal Structure: TEM allows for visualization of the internal structure of mitochondria, including the cristae (folded membranes) and matrix. This level of detail is crucial for understanding mitochondrial function.

* Electron Staining: TEM uses heavy metal stains that enhance the contrast of the mitochondria, making them easier to see against the background of the cell.

While a light microscope can be used to observe yeast cells, it won't reveal the details of their internal organelles like mitochondria.