Bacteria
Bacteria are single-celled prokaryotes found everywhere.
About this topic
Bacteria are microscopic single-celled prokaryotes, with a cell wall, no nucleus and DNA in a loop plus plasmids. Shapes include cocci (spheres), bacilli (rods) and spirilla (spirals). They reproduce rapidly by binary fission, as often as every 20 minutes in ideal conditions.
Many are helpful: gut bacteria aid digestion and make vitamins, decomposers recycle nutrients, nitrogen-fixing bacteria feed plants, and Lactobacillus makes yoghurt. Others cause disease, such as Salmonella in food poisoning, Streptococcus in sore throats and Mycobacterium in tuberculosis. Pathogenic bacteria harm us by multiplying quickly and releasing toxins.
Starting with one bacterium dividing every 20 minutes, after 10 hours there would be 2 to the power 30, over a billion. This explains how infections can take hold quickly and why resistance spreads: antibiotics kill most bacteria, but any resistant survivors multiply, so overuse and unfinished courses promote resistant strains like MRSA.
Bacteria are also used in genetic engineering, such as producing insulin. A common mistake is saying antibiotics work on viruses; they do not. Another is calling all bacteria harmful, when most are harmless or essential.
Key ideas
- Shapes: cocci, bacilli, spirals
- Reproduce by binary fission
- Some cause disease, many are helpful
Quick check
Use cases: where Bacteria helps
- Homework: review the key idea behind Bacteria before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Bacteria without notes.
- Visual learning: play with the interactive lab to see how Bacteria changes when you adjust its inputs.
- Teaching a friend: explain Bacteria in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Bacteria?
Bacteria are single-celled prokaryotes found everywhere.
What will I learn in Bacteria?
Shapes: cocci, bacilli, spirals. Reproduce by binary fission. Some cause disease, many are helpful.
Is Bacteria part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Bacteria lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Bacteria?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.