Summary
Permanent changes in the DNA sequence that can be harmless, harmful or occasionally beneficial.
In depth
Mutations occur from replication errors, chemicals, UV or ionising radiation. Those in gametes are heritable, while somatic mutations affect only the individual (such as cancer). Most are neutral, but some are harmful, and rarely beneficial, providing raw material for evolution.
Mutation rates in humans are about 1 in 100 million bases per generation, still yielding around 60 new mutations per child.
Mutation rates in humans are about 1 in 100 million bases per generation, or roughly 60 new changes in each child. Mutagens include UV light (thymine dimers), X-rays (breaks), chemicals such as benzo[a]pyrene in smoke and base analogues. Cells have repair systems; failures cause xeroderma pigmentosum and some cancers.
Mutations are random with respect to need, as shown by the Luria-Delbruck experiment (1943) with bacteria and phage. Beneficial mutations, such as lactase persistence or CCR5-delta32 conferring HIV resistance, are rare but vital for evolution.
Common mistake: assuming mutations are always harmful; many are neutral and some are beneficial.
Frequently asked questions
What is Mutations?
Permanent changes in the DNA sequence that can be harmless, harmful or occasionally beneficial.
Which area of biology covers Mutations, and how advanced is it?
Mutations is one of the 54 topics in Genetics. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Heritability, Transposable Elements, Pleiotropy.
Can you give an example of Mutations?
Lactase persistence in adults arose by mutations in the regulatory region of the lactase gene.
What should I learn before Mutations?
Mutations is a Beginner topic, so no earlier topic is required. Other Beginner topics in Genetics that pair well with it include Heredity, Gene, Allele.
What topics are related to Mutations?
The closest topics to Mutations are Heritability, Transposable Elements, Pleiotropy, Allele. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Mutations?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Mutations. To practise the whole of Genetics, use the Genetics quiz.
How is Mutations different from Heritability?
Mutations: Permanent changes in the DNA sequence that can be harmless, harmful or occasionally beneficial. Heritability: The proportion of phenotypic variation in a population attributable to genetic differences. Read both side by side and note what each one explains.
What is a common mistake about Mutations?
Assuming mutations are always harmful; many are neutral and some are beneficial.
How should I study Mutations 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 Heritability and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.