Pearson Edexcel · GCSE · Biology
Course version: 1BI0 · Version from Sept 2016
5.7B Describe the lifecycle of a virus, including lysogenic and lytic…
Full specification wording
Topic 5 – Health, disease and the development of medicines: 5.7B Describe the lifecycle of a virus, including lysogenic and lytic pathways
A virus is not a cell; it must enter a host cell to replicate.
Checked against the Pearson Edexcel 1BI0 specification (opens in a new tab) on .
- Point 7 of 21
Study notes
From the checked teaching notes for this specification point.
The idea
A virus is not a cell; it must enter a host cell to replicate. In the lysogenic pathway the virus inserts its genetic material into the host DNA, and the host cell continues to divide, copying the viral genetic material without immediately making new virus particles. A trigger can switch the virus to the lytic pathway. In the lytic pathway the host cell makes new viral components, assembles new virus particles, and the host cell bursts (lyses), releasing the particles to infect further cells. Describe the sequence: attachment and entry, then either the lysogenic or lytic route, then release. Use the terms genetic material, host cell, replicate and lyse accurately, and state that the lytic pathway destroys the host cell while the lysogenic pathway does not immediately do so.
What earns the marks
- A virus attaches to and enters a host cell before it can replicate, because it is not a cell itself.
- In the lysogenic pathway the viral genetic material is inserted into the host DNA and copied as the host cell divides, without immediate production of new virus particles.
- A trigger can switch the virus from the lysogenic pathway to the lytic pathway.
- In the lytic pathway the host cell makes new viral components, new virus particles are assembled, and the host cell bursts (lyses) to release them.
- Released virus particles infect further host cells, continuing the lifecycle.
Common mistakes and how to put them right
Saying a virus reproduces by itself outside a host cell.
Put it right: A virus must enter a host cell to replicate.
Confusing the pathways, claiming the lytic pathway inserts viral DNA into host DNA without destroying the cell.
Put it right: The lytic pathway produces new particles and lyses the host cell.
Describing the lysogenic pathway as immediately bursting the host cell.
Put it right: Viral genetic material is copied with the host DNA and the cell is not immediately destroyed.
Exam tips
- Sequence the stages in order: entry, then lysogenic or lytic, then release.
- Use the words lysogenic and lytic correctly and state which one destroys the host cell.
- State that a trigger can switch a lysogenic virus to the lytic pathway.
Try the lesson
The start of the Topic 5 – Health, disease and the development of medicines: 5.7B Describe the lifecycle of a virus, including lysogenic and lytic pathways lesson, made from checked teaching notes for this specification point.
Have a go first
In the lytic pathway of a virus, what happens to the host bacterial cell at the end of the cycle?
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