is an organism that has prokaryotic DNA, and can live in soil, water, plants and animals. A has a protein coat, DNA or RNA but no replication machinery. are eukaryotes that can be unicellular or multicellular and have cell walls that contain chitin. are eukaryotic, unicellular and motile. are worms and eukaryotic parasites.

: Organism capable of causing disease

: Organism which colonizes the host but causes no disease in normal circumstances

The viral replication cycle: A of the virus to to the host cell. Entering of the virus into the host cell. Ucoating of the virus. R of viral RNA or DNA into two strands. I of the viral DNA into the host cell's DNA. Production of the proteins coded for by the viral RNA or DNA upon replication of the host cell or protein synthesis. Assembly of the viral proteins into daughter viruses. R of the virus from the host cell.