Final answer:
Cellular microbes are either prokaryotes like bacteria and archaea, which lack a true nucleus, or eukaryotes such as protozoa and fungi, which have a nucleus. Viruses are acellular and do not fit into either category since they are not living cells and require a host to replicate.
Step-by-step explanation:
Cellular microbes can be divided into two main types: prokaryotes and eukaryotes. Prokaryotic microbes include all the organisms in the domains Archaea and Bacteria. These cells lack a nucleus and other membrane-bound organelles, and their DNA is not housed within a true nucleus. Examples of prokaryotic microbes include bacteria commonly found on earth, some of which are pathogens that can cause disease.
Eukaryotic microbes, on the other hand, are a diverse group that includes organisms with a well-organized, membrane-bound nucleus. This group encompasses a wide variety of species, including protozoa, fungi, and some algae, with different life cycles, nutritional needs, and some of them are responsible for significant diseases like malaria and giardiasis.
It is important to note that viruses, although often studied alongside microbial life, are neither prokaryotes nor eukaryotes. Viruses are acellular (not considered living cells) and require a host to replicate. They consist of a nucleic-acid core surrounded by a protein capsid and possibly an outer lipid envelope, but do not have a cellular structure and therefore cannot be classified within the same system as cellular microbes.