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In the first part of this series about viruses, we looked at general virus structure and function. As is true with most organisms, structure and function are thoroughly intertwined. This week we continue the series with a look at plant viruses and viroids.
Plant Viruses
Plant viruses are similar to animal viruses in most basic characteristics but they can also be markedly different. Most plant viruses have RNA as the genetic material.
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| Image copyright Dennis Kunkel. | |
There are two common mechanisms that plant viruses use to spread:
Horizontal Transmission
The virus is received from an external source. In order to "invade" the plant, the virus must penetrate the plant's outer protective layer known as the epidermis (epi-, -dermis). Plants that have been damaged by the weather, insects, etc. are typically more susceptible to the virus.
Vertical Transmission
In vertical transmission, the virus is inherited from a parent. This transmission can occur in both asexual and sexual reproduction.
In most cases, scientists have been unable to find cures for plant viruses, so scientists have been focusing on reducing the occurrence and transmission of the viruses.
Viroids
Viroids are tiny strands of RNA, usually only a few hundred nucleotides long. Viroids can interfere with a plant's metabolism.
Generally speaking, where viroids come from and how they can disrupt the host cell are not known.
Share Your Opinions
What do you think? How does the structure of a plant virus or viroid help determine its function? Would you classify a virus as living or nonliving? Come on over to the Biology Forum and share your thoughts, opinions and feelings. Until next time...
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