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Questions and Answers
What type of genetic material do viruses possess?
What type of genetic material do viruses possess?
Which statement accurately describes the reproductive capability of viruses?
Which statement accurately describes the reproductive capability of viruses?
What constitutes the protective outer layer of a virus?
What constitutes the protective outer layer of a virus?
Why are viruses considered non-living by most virologists?
Why are viruses considered non-living by most virologists?
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What is a bacteriophage?
What is a bacteriophage?
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Who developed the first vaccine against smallpox?
Who developed the first vaccine against smallpox?
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What year did Robert Koch live until?
What year did Robert Koch live until?
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What was the main contribution of Charles Chamberland in the late 19th century?
What was the main contribution of Charles Chamberland in the late 19th century?
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What significant theory did Robert Koch and Louis Pasteur propose in the 1880s?
What significant theory did Robert Koch and Louis Pasteur propose in the 1880s?
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What did Dimitri Ivanovski's experiments demonstrate about tobacco mosaic virus?
What did Dimitri Ivanovski's experiments demonstrate about tobacco mosaic virus?
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Which microbiologist coined the term 'virus'?
Which microbiologist coined the term 'virus'?
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What is one of Koch's postulates?
What is one of Koch's postulates?
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In the early 20th century, what significant discovery did Frederick Twort make?
In the early 20th century, what significant discovery did Frederick Twort make?
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What does the hieroglyph from Memphis depict?
What does the hieroglyph from Memphis depict?
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What practice involved the inhalation of dried crusts from smallpox lesions?
What practice involved the inhalation of dried crusts from smallpox lesions?
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Who is credited with the first successful vaccination against smallpox?
Who is credited with the first successful vaccination against smallpox?
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What was the significant outcome of Edward Jenner's experiment on July 1st, 1796?
What was the significant outcome of Edward Jenner's experiment on July 1st, 1796?
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By what year was smallpox endemic in China?
By what year was smallpox endemic in China?
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What did Edward Jenner observe in Sarah Nelmes that led him to investigate vaccination?
What did Edward Jenner observe in Sarah Nelmes that led him to investigate vaccination?
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What were the modified methods of variolation developed after the original practice?
What were the modified methods of variolation developed after the original practice?
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What is the name of the milkmaid involved in Jenner’s pivotal experiment?
What is the name of the milkmaid involved in Jenner’s pivotal experiment?
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What did Felix d'Herelle contribute to virology?
What did Felix d'Herelle contribute to virology?
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Which technique was NOT mentioned as helpful in the development of virology?
Which technique was NOT mentioned as helpful in the development of virology?
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What was the main substance found in the tobacco mosaic virus as discovered by Wendell Stanley?
What was the main substance found in the tobacco mosaic virus as discovered by Wendell Stanley?
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Which virus vaccine was developed by Theiler and is still in use today?
Which virus vaccine was developed by Theiler and is still in use today?
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In the comparison of viruses with other unicellular microorganisms, which property is unique to viruses?
In the comparison of viruses with other unicellular microorganisms, which property is unique to viruses?
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Which of the following is NOT a characteristic of viruses based on the comparison table provided?
Which of the following is NOT a characteristic of viruses based on the comparison table provided?
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What significant technological advancement allowed scientists to visualize viruses for the first time?
What significant technological advancement allowed scientists to visualize viruses for the first time?
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Which of the following statements about viruses is accurate?
Which of the following statements about viruses is accurate?
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Who won the Nobel Prize in 1951 for the development of a safe and effective vaccine?
Who won the Nobel Prize in 1951 for the development of a safe and effective vaccine?
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Which of the following is a property of viruses, as noted in the comparison table?
Which of the following is a property of viruses, as noted in the comparison table?
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What is an example of an atypical virus-like agent?
What is an example of an atypical virus-like agent?
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Which theory suggests that viruses may have originated from more complex organisms?
Which theory suggests that viruses may have originated from more complex organisms?
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Which of the following statements about satellite viruses is true?
Which of the following statements about satellite viruses is true?
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What type of nucleic acid do viroids contain?
What type of nucleic acid do viroids contain?
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How do prions differ from viruses in terms of nucleic acid content?
How do prions differ from viruses in terms of nucleic acid content?
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In the context of virology, what is the significance of 'helper viruses'?
In the context of virology, what is the significance of 'helper viruses'?
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Which characteristic is shared by both viruses and prions?
Which characteristic is shared by both viruses and prions?
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What is the usual replication site for viroids?
What is the usual replication site for viroids?
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Study Notes
History of Viruses
- Earliest written record of a virus infection dates back to approximately 3700 BC.
- A hieroglyph from Memphis, Egypt, depicts a priest, Ruma, exhibiting signs of paralytic poliomyelitis.
- In 1196 BC, Ramesses V, died of smallpox at around age 35.
- Smallpox was endemic in China by 1000 BC.
- Survivors of smallpox outbreaks were found to be protected.
- Variolation involved inhaling dried smallpox lesion crusts or, later, inoculating the pus into a scratch on a child's forearm.
Edward Jenner
- In the late 18th century, Edward Jenner observed a milkmaid, Sarah Nelmes, who had previously contracted cowpox and was subsequently immune to smallpox.
- On May 14, 1796, Jenner used cowpox material from Sarah Nelmes to successfully vaccinate an eight-year-old boy, James Phipps, against smallpox.
- Jenner's work led to the development of the first vaccine, and smallpox has been largely eradicated.
Koch's Postulates and Germ Theory
- Koch's postulates outline criteria for establishing a link between a microorganism and a disease: the agent must be present in every case, isolated from the host, and reproducing the disease when inoculated into a healthy host, and the same agent recovered.
- The germ theory of disease, jointly proposed by Robert Koch and Louis Pasteur in the 1880s, emphasized the role of microorganisms in causing diseases.
Filterable Agents
- In the late 19th century, Charles Chamberland developed a porcelain filter for virology research.
- Dimitri Ivanovski used this to study the tobacco mosaic virus, showing infectious agents smaller than bacteria.
- This work proved that viruses were distinct from bacteria but could still cause diseases.
- Martinus Beijerinck subsequently coined the term "virus."
Viruses in the 20th Century
- Frederick Twort discovered that bacteria could be infected by viruses.
- Felix d'Herelle demonstrated the ability of viruses to kill bacteria in cell cultures.
- Wendell Stanley crystallized the tobacco mosaic virus, revealing it was mostly protein.
- Viruses were separated into protein and nucleic acid parts.
- Electron microscopy provided the first visualization of viruses.
- John Enders, Thomas Weller, and Frederick Robbins developed human tissue culture techniques to study viruses, which helped produce the first polio vaccine.
Viruses: Filterable Agents (Animal, Human, and Plant)
- Yellow fever vaccine developed in mice - the 17D strain continues to be highly effective.
Techniques in Virology
- Cell culture
- Ultracentrifugation
- Electron microscopy
- Immunological techniques
- Radioisotopes
- Gel electrophoresis
- Recombinant DNA techniques
Definition of Viruses
- Viruses are submicroscopic particles that infect cells.
- Viruses replicate only within a host cell; they cannot reproduce independently.
- Viruses consist of genetic material (DNA or RNA) enclosed by a protective protein coat (capsid).
- Bacteriophages are viruses that infect bacteria.
Origin of Viruses
- Hypothesized origins of viruses include: regressive (degenerative), discard (escape), and coevolution theories.
Importance of Virology
- Understanding dangerous viruses is crucial.
- Some viruses are useful; for instance, in vaccine production.
Atypical Virus-like Agents
- Virions
- Viroids
- Satellites (Satellite Viruses, Virusoids)
- Prions
- Pseudovirions
Satellites and Viroids
-
Satellites Viroids Helper virus - Proteins encoded + Genome Replication Enzymes of helper virus Replication Site As helper (C or N) Type of NA and its length ss circular DNA molecule, 500-2000 nucleotides
Prions and Viruses
-
Prion Virus NA - Contain Protein + encoded by cellular gene UV and Heat effect + Under E.M. Rod/Filamentous Ab Production - Inflammation Production -
Are Viruses Alive?
- Most virologists consider viruses non-living, similar to obligatory intracellular parasites.
- Viruses are characterized as both living and non-living.
- Viruses are not composed of cells.
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Description
Explore the fascinating history of viruses, from ancient infections to the pioneering work of Edward Jenner in developing the first vaccine. This quiz covers key milestones in the understanding of viral diseases, including the impact of smallpox and Koch's postulates. Test your knowledge about this crucial aspect of medical history.
