Cells: Structure & Replication of Viruses

Question 1

Are viruses cells and are they alive?

Answer 1

• Viruses are acellular
• Viruses are not alive
• Viruses are just nucleic acids surrounded by proteins

Question 2

How do viruses differ from bacteria?

Answer 2

• Viruses have no:

• Cell surface membrane
• Cytoplasm
• Ribosomes

• Viruses do have:

• A capsid (protein coat)
• Genetic material
• Attachment proteins
• These are attached to the protein coat and let the virus cling onto a suitable host cell

Question 3

Describe how viruses replicate

Answer 3

• Attachment - virus attaches to host cell receptor proteins
• Entry - genetic material is released into the host cell
• Synthesis - genetic material and proteins are replicated by host cell organelles
• Assembly - viral components assemble
• Release - replicated viruses released from host cell