Describe viral replication - AQA - A-Level Biology - Question 4 - 2022 - Paper 1

Viral replication involves several critical steps:

1. Attachment: The virus attaches to the host cell via specific attachment proteins that bind to receptor sites on the host's cell membrane.

2. Entry: The viral nucleic acid is then introduced into the host cell, usually after the viral envelope fuses with the cell membrane or through endocytosis.

3. Replication: Once inside, the viral nucleic acid is replicated using the host's cellular machinery. In some viruses, such as retroviruses, the enzyme reverse transcriptase converts RNA into DNA.

4. Production of Viral Components: The host cell starts to produce viral proteins and enzymes necessary for creating new virus particles.

5. Assembly: Newly synthesized viral components are assembled into complete virus particles.

6. Release: Finally, the new viruses are released from the host cell, either through lysis (the cell breaks apart) or by budding off from the cell membrane.