What is the structure and function of a virus?
Do you want to know about all 4?? A virus is not a cell, nor even considered a living thing. It is a simple structure usually made of a protein coat with a piece of nucleic acid (DNA or RNA) inside. That’s it! It doesn’t feed, respire or do anything else that living organisms do except REPRODUCE. To reproduce it has to hijack another cell. It takes over the host cell to make more virus particles and no doubt lives happily ever after! The host usually suffers, sometimes fatally! All the other organisms you mentioned are cellular. Bacteria are single celled and rather primitive prokaryotes (don’t have a nucleus); protoctista (proper name for protozoa) are single celled but quite complex and do have a nucleus (eukaryotic); fungi are also complex (eukaryotic) and can be single celled like a yeast or multicellular like mushrooms!
