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1. What is the role of viral surface proteins in the molecular basis of infectious disease? Provide examples
and explain their significance in host-cell interaction.
Answer: Viral surface proteins play a crucial role in the molecular basis of infectious diseases. For instance,
the hemagglutinin protein of the influenza virus facilitates viral attachment and entry into host cells. The
surface protein spike (S protein) of SARS-CoV-2 enables viral entry into human lung cells via binding to
ACE2 receptors. Understanding the significance of viral surface proteins helps in designing targeted
therapeutics and vaccines.
2. Discuss the molecular mechanisms of antibiotic resistance in bacteria. How does the acquisition of
resistance genes impede treatment of infectious diseases?
Answer: Antibiotic resistance in bacteria arises from various molecular mechanisms such as mutation or
horizontal gene transfer. For instance, the acquisition of resistance genes through plasmids or transposons
allows bacteria to produce enzymes that inactivate antibiotics or alter their target sites. This impedes
treatment as the effectiveness of antibiotics is reduced, leading to persistent infections and limited treatment
options.
3. Describe the molecular basis of host defense mechanisms against viruses. How does the innate immune
response recognize and eliminate viral pathogens?
Answer: The innate immune response acts as the first line of defense against viral pathogens. Pattern
recognition receptors (PRRs) located on host cells can recognize molecular patterns unique to viruses, such
as viral nucleic acids or viral proteins. This recognition triggers the production of interferons and other
cytokines, which activate antiviral pathways, inhibit viral replication, and recruit immune cells to eliminate
the viral infection.
4. Explain the role of virulence factors in the pathogenesis of infectious diseases. Provide examples and
describe their molecular mechanisms.
Answer: Virulence factors are molecules produced by pathogens that contribute to the development and
severity of infectious diseases. For example, bacterial toxins such as cholera toxin and pertussis toxin
disrupt host cell signaling and immune responses. The molecular mechanisms of virulence factors often
involve binding to host cell receptors, modifying intracellular signaling pathways, or evading immune
surveillance, ultimately facilitating pathogen survival and dissemination.
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