AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
It is difficult to develop drugs that kill viruses without also damaging…
Full specification wording
Antibiotics and painkillers: It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
Viruses are not cells; they reproduce inside host cells, using the host's own machinery and structures to copy themselves.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 8 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Viruses are not cells; they reproduce inside host cells, using the host's own machinery and structures to copy themselves. A drug that blocks viral replication therefore risks blocking processes that human cells also use, so it may harm the body's tissues. This is why antibiotics, which target bacterial structures such as cell walls, do not work on viruses, and why developing antiviral drugs is difficult. Because the virus is hidden inside cells and relies on the host's cellular mechanisms, it is hard to reach and destroy the virus without damaging those host cells.
What earns the marks
- Viruses reproduce inside host cells, so a drug must enter those cells to reach the virus.
- Viruses use host cell machinery to replicate, so drugs that block this process often affect normal body cells.
- Antibiotics target bacterial structures such as cell walls, which viruses do not have, making antibiotics ineffective against viruses.
- Antiviral drugs must be highly selective, which is difficult because viruses rely on the host's own cellular processes.
- Damage to body tissues can occur because the drug's action may disrupt normal host cell functions.
Common mistakes and how to put them right
Thinking antibiotics can treat viral infections.
Put it right by stating that antibiotics act on bacteria, not viruses, because viruses lack bacterial cell walls.
Assuming viruses are cells.
Put it right by describing viruses as non-cellular particles that reproduce inside host cells.
Believing antiviral drugs are harmless because they target viruses.
Put it right by explaining that shared host-cell machinery means side effects and tissue damage are possible.
Exam tips
- Link the difficulty of developing drugs to the virus's intracellular life cycle, not just to the virus being small.
- Use the contrast with antibiotics to show why bacterial targets are easier to hit selectively without harming human cells.
- When explaining tissue damage, refer to the drug affecting host cell processes as well as viral replication.
Try the lesson
The start of the Antibiotics and painkillers: It is difficult to develop drugs that kill viruses without also damaging the body’s tissues. lesson, made from checked teaching notes for this specification point.
Have a go first
Why is it difficult to develop drugs that kill viruses without also damaging the body's tissues?
Listen
Viruses are not cells; they reproduce inside host cells, using the host's own machinery and structures to copy themselves. A drug that blocks viral replication therefore risks blocking processes that human cells also use, so it may harm the body's tissues. This is why antibiotics, which target bacterial structures such as cell walls, do not work on viruses, and why developing antiviral drugs is difficult. Because the virus is hidden inside cells and relies on the host's cellular mechanisms, it is hard to reach and destroy the virus without damaging those host cells. A strong answer earns marks for these points. Viruses reproduce inside host cells, so a drug must enter those cells to reach the virus. Viruses use host cell machinery to replicate, so drugs that block this process often affect normal body cells. Antibiotics target bacterial structures such as cell walls, which viruses do not have, making antibiotics ineffective against viruses. Antiviral drugs must be highly selective, which is difficult because viruses rely on the host's own cellular processes. A common slip: Thinking antibiotics can treat viral infections. Instead, stating that antibiotics act on bacteria, not viruses, because viruses lack bacterial cell walls. Exam tip: Link the difficulty of developing drugs to the virus's intracellular life cycle, not just to the virus being small.
Key words
Say what each word means before you turn the card.
Viral replication inside host cells
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Selectivity of drug action
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Antibiotics versus antivirals
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Side effects and tissue damage
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See every definition
- Viral replication inside host cells
- Viruses reproduce inside host cells, using the host's own machinery and structures to copy themselves.
- Selectivity of drug action
- Antiviral drugs must be highly selective, which is difficult because viruses rely on the host's own cellular processes.
- Antibiotics versus antivirals
- Antibiotics target bacterial structures such as cell walls, which viruses do not have, making antibiotics ineffective against viruses.
- Side effects and tissue damage
- Damage to body tissues can occur because the drug's action may disrupt normal host cell functions.
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