Viral Diseases (AQA GCSE Biology)

Viruses: Basics

• There are many common diseases caused by viruses; for example, the common cold and the flu are caused by viruses

• Viruses do not fulfil the 7 life processes, therefore, they are not usually classified as living organisms

  • Viruses do not have nuclei, organelles, or cytoplasm like cells do, and so they have no way to monitor or create change in their internal environment

• Viruses reproduce rapidly by inserting their genetic material into host cells and creating new protein capsules to build new viral particles

• Once many copies have been made, the host cell may burst open releasing the viral particles which can go on to infect other cells

Measles

• Measles is a highly contagious and a potentially serious viral infectious disease that can be fatal if complications arise

• Measles is most often seen in children – most young children are vaccinated against it

Measles table

HIV

• HIV (Human Immunodeficiency Virus) is a virus that can eventually lead to Acquired Immunodeficiency Syndrome (AIDS)

HIV table

Tobacco Mosaic Virus

• Tobacco mosaic virus (TMV) was the first virus to be isolated by scientists

• It is a widespread plant pathogen that infects about 150 species of plants including tomato plants and cucumbers

TMV table