1. Beyond Viruses…… Can create an “infection” that can lead to the death of the “infected organism? …appears to be able to replicate itself… …is not a bacteria! …is smaller than a virus? …is not a virus! …contains genetic information! …structurally like the “guts”of a virus!

2. VIROIDS: The Plant Invaders… A VIROID is a… VIR (virus) OID (like) particle. Viroids are“sub-viruses” composed exclusively of a single circular strand of nucleic acid (RNA) that codes for a single protein.

3. VIROIDS: DID YOU KNOW VIROIDS… are infectious particles. are smaller than any of the known viruses. range in size from approximately 20 nm (8 x 10 -7 inches)... are just 100 times larger than Atoms which measure in at.1 nanometers. cause certain plant and human diseases. consists only of Nucleic Acid (RNA).

4. VIROIDS: The Potato “Nose”… Normal Potatoes Infected Potatoes

5. VIROIDS: The Potato “Nose”… In Class Reading… VIROIDS!

6. VIROIDS : Are VIROIDs a new form of life? 1- Are VIROIDs made of cells? NO 2- Are VIROIDs organized? YES 3- Do VIROIDs use energy? NO 4- Are VIROIDs responsive? NO

7. 5- Do VIROIDs grow? (enlarge and divide) NO 6- Do VIROIDs reproduce? YES ~they recruit their host’s cellular machinery to replicate it RNA using the original as a template 7- Do VIROIDs adapt? YES/NO, ~ do mutate into other viable forms. VIROIDs : Are VIROIDs a new form of life?

8. 8- Do VIROIDs die? NO, however like all nucleic acids, their structure can be degraded by catalysts or UV light 9- Do VIROIDs come from pre-existing viroids? YES ~ existing VIROIDs are the templates for the next generation of replicants VIROIDs : Are VIROIDs a new form of life?

9. VIROIDs : Origin & Structure v