Biology A-Level- Viruses

• What are viruses?

  Acellular nucleic acids surrounded by dead proteins
• What are host cells?

  The cells that viruses invade and reproduce themselves in
• What is the role of attachment proteins?


  Allow the virus to cling onto a suitable host cell
• Why don't viruses undergo cell division?

  Because they aren't alive
• What are the 5 stages of viral replication?

  1. Virus attaches to host cell receptor proteins. 2. Genetic material is released into the host cell. 3. Genetic material and proteins are replicated using the host cell's machinery .4. Viral components assemble 5. Replicated viruses are released from the host cell
• Why can some viruses infect 1 type of cell and others can infect lots of different cells?

  Because different viruses have different attachment proteins and require different receptor proteins on host cells
• Why cant antibiotics be used to treat viruses?

  Viruses use the host cell's enzymes and ribosomes so because human viruses use human enzymes and ribosomes to replicate, antibiotics cant inhibit them because they don't target human processes
• What are antiviral drugs designed to do?

  Target the few virus-specific enzymes that exist
• How do antibiotics kill bacteria?

  By interfering with their metabolic reactions by targeting the bacterial enzymes and ribosomes used in these reactions
• Why are antibiotics designed to target bacterial enzymes and ribosomes?

  So they don't damage human cells