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Questions and Answers
Which of the following accurately describes the nature of viruses?
What type of nucleic acid can a virus contain?
How do viruses reproduce within a host cell?
Which statement best describes the metabolic capabilities of viruses?
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What role do the surface molecules of a virus serve?
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What term was first proposed by Dmitri Ivanoski in the 1890s?
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What is a key characteristic that defines viruses?
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Which of the following best describes the structure of a virus?
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Which scientist postulated that rabies was caused by a living thing smaller than bacteria?
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How do viruses differ from bacteria in terms of their biological classification?
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What is the size range of viruses?
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What role do viruses play in the evolution of living organisms?
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What does the term 'obligate intracellular parasite' imply about viruses?
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Study Notes
The Search for the Elusive Virus
- Louis Pasteur theorized rabies was caused by a "living thing" smaller than bacteria in 1884.
- Dmitri Ivanoski first proposed the term "virus," meaning "poison," in the late 19th century.
- Ivanoski and Beijerinck demonstrated that a tobacco disease was caused by a virus in the 1890s.
- Virology became a comprehensive field in the 1950s.
- Viruses are smaller than bacteria and other living cells.
Viruses in the Biological Spectrum
- There is no universal consensus on the origins of viruses.
- Viruses may be the most abundant microbes on Earth.
- Viruses played a role in the evolution of Bacteria, Archaea, and Eukarya.
- Viruses are obligate intracellular parasites, meaning they must infect a host cell to replicate and survive.
- They are parasites because they require a living host cell to reproduce.
- Viruses can not survive without a host cell.
Properties of Viruses
- Viruses infect bacteria, protozoa, fungi, algae, plants, and animals.
- Viruses are ultramicroscopic, ranging in size from 20 nanometers to 450 nanometers in diameter.
- Viruses are not cellular and have a compact, economical structure consisting of DNA or RNA encased in a protein.
- Viruses are not considered to be living organisms because they lack the ability to perform the functions of life independently.
- As inactive macromolecules, viruses are inert outside of host cells and only become active upon entry into the host cell.
- Viruses contain either DNA or RNA, never both.
- Viruses are encased in a protein shell called a capsid that surrounds the nucleic acid core of the virus.
- Viral nucleic acid can be double-stranded DNA, single-stranded DNA, single-stranded RNA, or double-stranded RNA.
- Molecules on the virus's surface enable specific attachment to the host cell.
Virus Replication
- Viruses replicate by taking control of the host cell's genetic material and regulating the synthesis and assembly of new viruses.
- Viruses lack most metabolic enzymes and protein synthesis machinery.
- Viruses can be described as "biological pirates" because they hijack the host cell's resources to create new viruses.
General Size of Viruses
- Most viruses are ultramicroscopic in size.
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Description
Explore the fascinating world of virology and the history surrounding the discovery of viruses. From Pasteur’s early theories to the established understanding of viruses as obligate intracellular parasites, this quiz covers key concepts and milestones in the field. Test your knowledge on properties, origins, and the role of viruses in the biological spectrum.
