Mutations
Mutations are changes to the DNA sequence.
About this topic
A mutation is a change in the DNA sequence. Point mutations alter a single base: substitutions may be silent, missense or nonsense; insertions or deletions cause frameshifts that disrupt the reading frame. Chromosomal mutations change larger sections or numbers of chromosomes, as in Down's syndrome.
Mutations arise from replication errors or from mutagens like UV radiation, X-rays and chemicals. Most are harmless or harmful, but some are beneficial and provide the variation that drives evolution. Mutations in gametes are inherited.
Sickle-cell anaemia is caused by a single base substitution that changes one amino acid in haemoglobin, making red blood cells bend into sickle shapes. A deletion of one base shifts the reading frame, changing every following codon, which is usually far more damaging. Some mutations are silent because of the redundancy of the code and have no effect.
Mutations arise from copying errors or damage by UV light, X-rays and chemicals such as those in tobacco smoke. Most are harmful or neutral, but a few are beneficial and give raw material for evolution, such as lactose tolerance in adults. Only mutations in gametes can be passed to offspring. Students often think all mutations are bad, or that they happen on purpose when needed; they are random.
Key ideas
- Substitution, insertion, deletion
- Some harm, some help, most are neutral
- UV and chemicals increase rates
Quick check
Use cases: where Mutations helps
- Homework: review the key idea behind Mutations before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Mutations without notes.
- Visual learning: play with the interactive lab to see how Mutations changes when you adjust its inputs.
- Teaching a friend: explain Mutations in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Mutations?
Mutations are changes to the DNA sequence.
What will I learn in Mutations?
Substitution, insertion, deletion. Some harm, some help, most are neutral. UV and chemicals increase rates.
Is Mutations 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 Mutations 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 Mutations?
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.