AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Viruses live and reproduce inside cells, causing cell damage.
Full specification wording
Communicable (infectious) diseases: Viruses live and reproduce inside cells, causing cell damage.
Viruses are much smaller than bacteria and are not cells.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 8 of 8
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Viruses are much smaller than bacteria and are not cells. They are obligate parasites: they can only reproduce inside a host cell. A virus attaches to a specific host cell, injects its genetic material, and uses the cell's machinery to make copies of its own genetic material and protein coat. These copies assemble into new virus particles. The host cell is often damaged or destroyed when the new viruses burst out, and this cell damage produces the symptoms of the viral disease. For example, influenza viruses infect cells lining the respiratory tract, damaging them and causing fever, cough and aching. Because viruses rely on host cells, antibiotics that target bacterial structures do not work against them. This explains why viral diseases such as measles and HIV are difficult to treat directly and why vaccination is so important.
What earns the marks
- Viruses are not cells and are much smaller than bacteria.
- Viruses are obligate parasites that can only reproduce inside a host cell.
- The virus uses the host cell's machinery to replicate its genetic material and make new virus particles.
- New virus particles are released, often destroying or damaging the host cell.
- Cell damage caused by viral replication produces the symptoms of the disease.
- Antibiotics do not kill viruses because viruses lack the bacterial structures that antibiotics target.
Common mistakes and how to put them right
Saying viruses are a type of bacterium.
Put it right by stating viruses are not cells and are much smaller.
Believing viruses can reproduce on their own.
Put it right by explaining they need a host cell's machinery.
Thinking antibiotics can treat viral infections.
Put it right by stating antibiotics target bacteria, not viruses.
Exam tips
- Use the phrase host cell and state that reproduction occurs inside it.
- Link cell damage directly to symptoms to show cause and effect.
- Contrast viruses with bacteria in one sentence to demonstrate understanding of why treatments differ.
Try the lesson
The start of the Communicable (infectious) diseases: Viruses live and reproduce inside cells, causing cell damage. lesson, made from checked teaching notes for this specification point.
Have a go first
Where do viruses live and reproduce?
Listen
Viruses are much smaller than bacteria and are not cells. They are obligate parasites: they can only reproduce inside a host cell. A virus attaches to a specific host cell, injects its genetic material, and uses the cell's machinery to make copies of its own genetic material and protein coat. These copies assemble into new virus particles. The host cell is often damaged or destroyed when the new viruses burst out, and this cell damage produces the symptoms of the viral disease. For example, influenza viruses infect cells lining the respiratory tract, damaging them and causing fever, cough and aching. Because viruses rely on host cells, antibiotics that target bacterial structures do not work against them. This explains why viral diseases such as measles and HIV are difficult to treat directly and why vaccination is so important. A strong answer earns marks for these points. Viruses are not cells and are much smaller than bacteria. Viruses are obligate parasites that can only reproduce inside a host cell. The virus uses the host cell's machinery to replicate its genetic material and make new virus particles. New virus particles are released, often destroying or damaging the host cell. A common slip: Saying viruses are a type of bacterium. Instead, stating viruses are not cells and are much smaller. Exam tip: Use the phrase host cell and state that reproduction occurs inside it.
Key words
Say what each word means before you turn the card.
Pathogen mechanisms
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Cell damage and symptoms
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Treatment and prevention
Try answering aloud or in your head before turning the card.
See every definition
- Pathogen mechanisms
- A virus attaches to a specific host cell, injects its genetic material, and uses the cell's machinery to make copies of its own genetic material and protein coat.
- Cell damage and symptoms
- The host cell is often damaged or destroyed when the new viruses burst out, and this cell damage produces the symptoms of the viral disease.
- Treatment and prevention
- Antibiotics that target bacterial structures do not work against viruses, which explains why vaccination is so important.
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