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What is the role of phylogenetic trees in understanding viruses?
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Phylogenetic trees help determine evolutionary relationships, which can be essential for tracing virus origins and understanding their evolution.
Define the regressive hypothesis regarding viral evolution.
The regressive hypothesis suggests that viruses were once free-living cells that lost complexity and became parasites.
Describe how oncogenic viruses contribute to cancer development.
Oncogenic viruses can integrate their genetic material into the host genome, disrupting normal cell regulation and leading to uncontrolled cell growth and cancer.
Why are viruses not considered living organisms?
Viruses are not considered living because they cannot reproduce independently; they require a host cell for replication.
What is the primary aim of antiviral drugs?
Antiviral drugs aim to manage symptoms and control viral replication rather than curing the infection entirely.
Describe the structure of a typical virus.
A typical virus consists of a nucleic acid core (either DNA or RNA), a protein coat called a capsid, and sometimes an additional envelope made of phospholipids.
What challenges do vaccines face in their effectiveness against viruses?
Vaccines can be less effective if virus strains mutate rapidly, as they may only target previous strains rather than current or emerging variants.
How do vaccines prepare the immune system against viruses?
Vaccines expose the immune system to viral components, allowing it to recognize and respond more effectively to future infections by stimulating the production of antibodies.
What are prions and how do they differ from viruses?
Prions are infectious protein particles that cause diseases by inducing abnormal folding of specific proteins, unlike viruses, which are composed of nucleic acids and proteins.
Compare the progressive hypothesis and the self-replicating hypothesis for viral evolution.
The progressive hypothesis posits that viruses originated from DNA or RNA that escaped host cells. In contrast, the self-replicating hypothesis suggests viruses arose from self-replicating genetic material or replicons.
List the stages of the viral replication cycle.
The stages are permissive binding to a host cell receptor, attachment, entry, replication and assembly of viral components, and egress of new virions either by cell lysis or budding.
What is the Baltimore classification system?
The Baltimore classification system categorizes viruses based on their morphology, genetics, and the method they use for mRNA production.
Explain the difference between enveloped and non-enveloped viruses.
Enveloped viruses have an outer lipid membrane derived from the host cell membrane, while non-enveloped viruses lack this lipid membrane.
Identify the key differences between acute, chronic, and asymptomatic viral infections.
Acute infections are short-term with rapid onset, chronic infections are long-term with possible persistent symptoms, and asymptomatic infections show no symptoms but can still spread the virus.
Explain the significance of host cell receptor specificity in viral infections.
For a virus to infect a cell, the host must possess specific receptors that can bind to the virus, making receptor specificity crucial for the virus's ability to attach and enter the host cell.
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