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Describe the role of the protein capsid in a virus.
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The protein capsid is a shell that encloses the genetic material of a virus, providing protection and aiding in the attachment to host cells.
What are the components of a virus's basic structure?
The basic structure of a virus includes genetic material (DNA or RNA), a protein capsid, and in some cases, a lipid envelope derived from the host cell membrane.
What percentage of the human genome consists of viral DNA remnants, and what does this indicate?
8% of the human genome consists of ancient viral remnants, illustrating past viral integration and the impact of viruses on genetic makeup.
In what ways do viruses contribute to the evolution of organisms?
Viruses contribute to evolution by integrating their genetic material into host genomes, which can lead to new genetic variations and traits over generations.
Explain the concept of 'obligate intracellular parasites' in the context of viruses.
Viruses are obligate intracellular parasites because they require a host cell's machinery to replicate, as they lack their own metabolic and protein synthesis enzymes.
Why is there debate among virologists regarding whether viruses are considered living organisms?
Some virologists argue viruses are living because they can direct cell processes to replicate. Others consider them non-living since they cannot replicate independently.
What is the significance of Louis Pasteur's rabies vaccine in the history of virology?
Louis Pasteur developed a rabies vaccine before the discovery of viruses, using dried spinal cords from infected animals. This was significant as rabies is 100% fatal without treatment.
What is the significance of electron microscopes in the study of viruses?
Electron microscopes allow scientists to visualize viruses, which are too small to be seen with light microscopes, and to study their detailed structure and components.
How do viruses achieve host cell specificity?
Surface molecules on viruses determine host cell specificity by recognizing and binding to specific receptors on the host cells, such as influenza viruses targeting respiratory cells.
How do bacteriophages differ in structure compared to other viruses?
Bacteriophages typically have more complex structures, often with specialized components such as a head for storing genetic material and a tail apparatus for injecting it into bacterial cells.
Explain the role of viruses in horizontal gene transfer.
Viruses facilitate horizontal gene transfer within the same generation, contributing to genetic variation and serving as a basis for gene therapy concepts.
Describe the experiment Dimitri Ivanovsky conducted that led to the discovery of viruses.
Ivanovsky studied tobacco mosaic disease and used porcelain filters to differentiate bacteria and viruses. He found that an infectious agent passed through the filters, indicating it was a virus.
Why can viruses not be seen with a light microscope?
Viruses are much smaller than bacteria, making them invisible to light microscopes and requiring electron microscopes for visualization.
Discuss the impact of viral gene integration on the human genome.
Viral gene integration has impacted the human genome by leaving remnants of viral DNA that make up approximately 8% of the genome, highlighting the evolutionary influence of viruses.
What genetic material do viruses contain, and is it ever both DNA and RNA?
Viruses contain either DNA or RNA as their genetic material, but never both.
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