Pathogens and Disease | 9-1 GCSE Science Biology | OCR, AQA, Edexcel

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They key points covered in this video include:
1. Pathogens
2. Bacteria
3. Viruses
4. Fungi
5. Protists

Pathogens

Communicable diseases are usually caused by pathogens. Pathogens are microorganisms that cause communicable diseases when they enter the body. There are several different types of pathogen - these can infect animals or plants. This includes bacteria, viruses, protists and fungi. Different types of pathogen cause different diseases and are spread in different ways.

Bacteria

Bacteria are tiny cells which rapidly reproduce inside the body. They may make you feel ill by producing toxins which damage tissues. Examples of bacterial diseases include chlamydia, gonorrhoea, tuberculosis, salmonella, cholera and stomach ulcers.

Viruses

Viruses, unlike bacteria, are not living cells. They cannot reproduce by themselves, but more copies can be made inside your cells by using the cells' machinery. Cells then burst to release the new copies of the virus - this obviously damages cells. An example of a virus is human immunodeficiency virus (HIV)

Fungi

Fungi are things like yeasts and moulds - some fungi can be pathogens. They may have hyphae (thread-like structures) which penetrate plants and/or animals to cause disease. They can be spread by the production of spores. Examples include Athlete's foot and Rose Black Spot disease.

Protists

Protists are eukaryotes, and most are single celled. Protists often get into an organism via a vector. For example, malaria is caused by protists which are carried by mosquitoes.

Summary

1. Pathogens are microorganisms that cause communicable diseases when they enter the body
2. Bacteria cause disease by producing toxins inside the body
3. Viruses cause disease by getting into and replicating inside the body's own cells
4. Fungi sometimes have hyphae (thread-like structures) which penetrate organisms to cause disease
5. Protists are eukaryotic and usually single celled organisms that cause disease - they may be spread by vectors (e.g. mosquitos)