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!

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.

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) .

VIROIDS: The Potato “Nose”…

Normal Potatoes

Infected Potatoes

VIROIDS: The Potato “Nose”…

In Class Reading…

VIROIDS!

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

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

template7- Do VIROIDs adapt?

YES/NO, ~ do mutate into other viable forms.

VIROIDs : Are VIROIDs a new form of life?

8- Do VIROIDs die? NO,

however like all nucleic acids, their structure can be degraded by catalysts or UV light9- 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?

VIROIDs : Origin & Structure

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