Summary
Living things too small to see without a microscope, including bacteria, archaea, protists, fungi and microscopic algae.
In depth
Microbes include bacteria, archaea, most protists, many fungi and viruses (not strictly alive). They inhabit every habitat, and a teaspoon of soil holds billions. They produced Earth's oxygen, drive nutrient cycles and live on and inside humans (around 38 trillion cells).
Most microbes are harmless or beneficial; only a small fraction cause disease.
Microbes are classified by cell type and metabolism. Pure cultures allow study of single species. Koch and Pasteur founded microbiology.
Key idea: microbes are everywhere and mostly beneficial.
Frequently asked questions
What is Microorganisms?
Living things too small to see without a microscope, including bacteria, archaea, protists, fungi and microscopic algae.
Which area of biology covers Microorganisms, and how advanced is it?
Microorganisms is one of the 54 topics in Microbiology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Bacteria, Protists, Pathogens.
Can you give an example of Microorganisms?
Gut bacteria help digest fibre and train the immune system.
What should I learn before Microorganisms?
Microorganisms is a Beginner topic, so no earlier topic is required. Other Beginner topics in Microbiology that pair well with it include Bacteria, Archaea, Bacterial Shapes.
What topics are related to Microorganisms?
The closest topics to Microorganisms are Bacteria, Protists, Pathogens, Protozoan Parasites. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Microorganisms?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Microorganisms. To practise the whole of Microbiology, use the Microbiology quiz.
How is Microorganisms different from Bacteria?
Microorganisms: Living things too small to see without a microscope, including bacteria, archaea, protists, fungi and microscopic algae. Bacteria: Single-celled prokaryotes found everywhere, vital for nutrient cycling, digestion and some disease. Read both side by side and note what each one explains.
How should I study Microorganisms step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Bacteria and explain the difference aloud. Finally, take the Microbiology quiz and come back to this page for any question you miss.