Final answer:
Viruses consist of a nucleic acid genome surrounded by a protein capsid and sometimes a lipid envelope with attachment spikes, requiring electron microscopy to be visualized. In contrast, cells, including prokaryotes, have complex structures with membranes and organelles and are observable with a light microscope. The main difference is that cells are living and replicate independently, while viruses require a host to replicate.
Step-by-step explanation:
Structure of Viruses vs Cells
The structure of a virus is significantly different from that of a cell. Viruses consist of a capsid, which is a protein coat that surrounds the viral genome, and in some cases, a viral envelope that surrounds the capsid. The capsid can have various shapes, such as icosahedral or helical. Some viruses have complex structures with additional features like tail fibers and spikes for attaching to host cells. For instance, the influenza virus has hemagglutinin (H) and neuraminidase (N) spikes. On the other hand, cells, including prokaryotic cells, are larger and much more complex, consisting of a cell membrane, cytoplasm, ribosomes, and DNA. Some cells also have cell walls and organelles.
Due to their small size, ranging approximately from 20 to 250 nanometers in diameter, virions require electron microscopy to be visualized. In contrast, cells can generally be seen using a light microscope since they are larger, often around 10 to 100 times the size of a virus. Recent discoveries have identified large viral species, such as Pandoravirus and Pithovirus, which approach the size of bacterial cells.
Prokaryotic cells and viruses are similar in that they both have genetic material and a protective coating, but prokaryotic cells are living entities with a metabolism and the capacity for independent reproduction, while viruses require a host to replicate.