16 Questions
What was the outcome of Wendell Stanley's experiment in 1935?
He crystallized the infectious particle, now known as tobacco mosaic virus (TMV).
What is the term for viruses that can replicate only within a host cell?
Obligate intracellular parasites.
What is the function of the tail fibers in a bacteriophage?
To attach to the host cell.
What is the term for a phage that reproduces only by the lytic cycle?
Virulent phage.
What is the term for the integrated viral DNA molecule in the lysogenic cycle?
Prophage.
What triggers the virus genome to exit the bacterial chromosome and switch to the lytic mode in a temperate phage?
Environmental signals.
What is the outcome when a prophage exits the bacterial chromosome?
The cell lyses, releasing phages
What is the purpose of viral envelopes?
To bind to specific receptor molecules on the surface of a host cell
What is the function of reverse transcriptase in retroviruses?
To copy the RNA genome into DNA
Why are vaccines effective against viral infections?
Because they stimulate the immune system to mount defenses against the harmful pathogen
What is the main difference between viral diseases in plants and animals?
Viral diseases in plants are spread horizontally, while in animals they are spread vertically
What is the function of plasmodesmata in plants?
To allow for infection to travel from cell to cell
What is the difference between viroids and prions?
Viroids are infectious RNA molecules, while prions are infectious proteins
What is the outcome when a virus infects a host cell?
The host cell dies, releasing new viruses
Why do emerging viruses suddenly become apparent?
Because they have jumped species and exchanged genetic information with other viruses
What is the economic impact of plant viral diseases?
A $15 billion loss annually, worldwide
Learn about the discovery of tobacco mosaic virus, its structure and how it differs from cells. Discover how researchers identified the virus and its impact on plants.
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