Examples of Viruses: Classification by Structure and Genome

📚 Quick Study Guide

• 🧬 Viral Structure: Viruses are composed of genetic material (DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have an envelope derived from the host cell membrane.
• 🔍 Classification by Structure:
  • icosahedral (e.g., adenovirus)
  • helical (e.g., tobacco mosaic virus)
  • complex (e.g., bacteriophage)
• 🧪 Classification by Genome: Viruses can have DNA or RNA genomes, which can be single-stranded (ss) or double-stranded (ds).
  • dsDNA viruses (e.g., herpesvirus)
  • ssDNA viruses (e.g., parvovirus)
  • dsRNA viruses (e.g., rotavirus)
  • (+)ssRNA viruses (e.g., poliovirus)
  • (-)ssRNA viruses (e.g., influenza virus)
  • Retroviruses (RNA viruses that use reverse transcriptase to make DNA, e.g., HIV)
• 📝 Key Concepts: Understanding viral structure and genome is crucial for developing antiviral therapies and vaccines.

🤔 Practice Quiz

1. Which of the following describes the protein coat surrounding a virus?
   1. Capsomere
   2. Capsid
   3. Envelope
   4. Genome
2. A virus with a genome consisting of double-stranded DNA is classified as:
   1. ssDNA virus
   2. dsDNA virus
   3. ssRNA virus
   4. dsRNA virus
3. Which structural shape is associated with the adenovirus?
   1. Helical
   2. Icosahedral
   3. Complex
   4. Spherical
4. HIV is an example of what type of virus?
   1. dsDNA virus
   2. ssDNA virus
   3. dsRNA virus
   4. Retrovirus
5. Influenza virus has which type of genome?
   1. (+)ssRNA
   2. (-)ssRNA
   3. dsDNA
   4. ssDNA
6. What is the function of reverse transcriptase in retroviruses?
   1. Replicating RNA from RNA
   2. Synthesizing DNA from RNA
   3. Translating viral proteins
   4. Degrading host DNA
7. Which of the following is NOT a common viral shape?
   1. Icosahedral
   2. Helical
   3. Complex
   4. Cubic