Virus
Contents
Key Stage 4
A clipart image of a virus.
Meaning
A virus is a type pathogen that can infect individual cells in an organism.
About Viruses
- Viruses are made from DNA or RNA and a protein sheath.
- Viruses cannot reproduce outside a host cell so they are not considered to be alive.
- When a virus comes in contact with a target cell it attaches itself to the cell membrane and then injects its DNA (or RNA) into the cell. Once this is done the DNA causes the cell to start making copies of the virus. When millions of copies have been made they burst out, killing the cell. These millions of viruses can then go on to infect other cells.
- Different viruses can only attach themselves to certain types of cell, so they can all have very different effects on the organism depending on which type of cell they infect.
Examples
- The measles virus causes causes a rash, blindness and brain damage.
- HIV causes a disease called AIDS which has the symptoms of a weakened immune system which leads to other infections.
- Tobacco Mosaic Virus is a virus which causes Tomato Plants and Tobacco Plants to grow slowly.
References
AQA
- Virus, pages 129, 138-41, 300, 304, GCSE Biology; Student Book, Collins, AQA
- Viruses, pages 124, 126, GCSE Combined Science Trilogy; Biology, CGP, AQA
- Viruses, pages 130, 132, GCSE Biology, CGP, AQA
- Viruses, pages 42, 44, GCSE Combined Science; The Revision Guide, CGP, AQA
- Viruses, pages 46, 47, GCSE Biology; The Revision Guide, CGP, AQA
- Viruses, pages 76-77, 84-85, 115, GCSE Biology; Third Edition, Oxford University Press, AQA
Edexcel
- Viruses, pages 153, 155-159, GCSE Biology, CGP, Edexcel
- Viruses, pages 39, 40, GCSE Combined Science; The Revision Guide, CGP, Edexcel
- Viruses, pages 55, 56, GCSE Biology; The Revision Guide, CGP, Edexcel
- Viruses, pages 87, 103, GCSE Biology, Pearson, Edexcel
- Viruses; life cycle, pages 106-107, GCSE Biology, Pearson, Edexcel
- Viruses; vectors for, pages 195, GCSE Biology, Pearson, Edexcel
OCR
- Viruses, pages 24-25, 209, 211, 215-216, 221, Gateway GCSE Biology, Oxford, OCR
- Viruses, pages 67, 68, 72, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
- Viruses, pages 91, 92, Gateway GCSE Biology; The Revision Guide, CGP, OCR