biology unit 2.5

• Microorganisms (microbes): Tiny organisms, usually unicellular, that can't be seen with the naked eye.

• Not all microbes cause disease: Many microbes are beneficial, playing a vital role in our environment and even our bodies.

• Disease-causing microbes: These are called pathogens and come in various forms:

• Bacteria: Single-celled organisms with cell walls, can cause a variety of diseases like strep throat and food poisoning.

• Viruses: Even smaller than bacteria, they invade and hijack host cells to reproduce, causing diseases like the common cold and HIV/AIDS.

• Protozoa: Single-celled eukaryotes, some can cause illnesses like malaria and amoebic dysentery.

• Fungi: Can range from microscopic yeasts to large mushrooms, some fungal species can cause infections like athlete's foot or ringworm.

• Worms: Parasitic worms can invade our bodies and cause diseases like tapeworm infections.

• How do pathogens cause disease? They disrupt normal bodily functions in various ways, like:

1. Multiplying and damaging tissues.

2. Releasing toxins (poisons).

3. Disrupting the immune system.

• Preventing the spread of disease:

1. Proper hygiene (washing hands, etc.)

2. Vaccinations.

3. Avoiding contact with those who are sick.