Introductory Microbiology Chapter 13 Viruses . B. Viral structures 1. Nucleic acid a. The viral genome can be linear, circular or segmented in different viruses 2. They have a polyhedral head and a helical tail sheath as well as tail fibers, and a baseplate with pins.
Envelopes are present only in some viruses.
Proteins and carbohydrates may also be present, for example as spikes. The envelope is acquired by budding out of the host cell b. As yet, no Genus and species names have been assigned, but names are descriptive of the virus. Need to make a positive sense strand before transcription. Need t DNA or RNA transcriptase enzyme to do this.