Genetics and evolution · BEGINNER LESSON
Mutation
A mutation is any change in the sequence of an organism’s genome, or the process that produces such changes. In many sources here, “DNA mutation” also means a change in DNA sequence that was not repaired by the cell.
What mutation is
A mutation is a change in the sequence of an organism’s genome, or the process that causes that change. In this lesson, genome means the full genetic material of an organism, and DNA means deoxyribonucleic acid, the molecule that stores genetic information in many organisms. One source here uses “DNA mutation” more narrowly for a single nucleotide change that was not repaired.
[1] What is mutation? A chapter in the series - PMC - NIH [2] pmc.ncbi.nlm.nih.gov · articles · PMC4563715Mutation—The Engine of Evolution: Studying Mutation and Its ...
What is measured
Scientists study mutation by asking how often changes happen, what kinds of changes appear, and where in the genome they occur. They also measure whether mutations are single-base changes, small insertions or deletions, or larger rearrangements such as duplications and inversions.
[1] What is mutation? A chapter in the series - PMC - NIH [2] pmc.ncbi.nlm.nih.gov · articles · PMC4563715Mutation—The Engine of Evolution: Studying Mutation and Its ... [3] Mechanism
How mutations arise
The sources describe four main causes: mutagens, which are agents such as ultraviolet radiation or certain chemicals that damage DNA; molecular decay, meaning spontaneous chemical reactions in DNA; errors during DNA repair; and errors during DNA replication, the copying of DNA before cell division. In bacteria, some mutation pathways are temporally regulated, meaning stress responses can turn them on when cells are poorly adapted to their environment.
[3] Mechanism [1] What is mutation? A chapter in the series - PMC - NIH
Patterns in the genome
Mutation does not always happen uniformly. One source reports that some stress-related mechanisms create hotspots near a DNA double-strand break, which is a cut in both strands of the DNA molecule. Mutations can also appear in clusters, so nearby changes may be more likely to occur together than expected by chance.
Why mutation matters and its limits
Mutations create genetic variation, and that variation is the raw material for evolution and natural selection. But mutations can also reduce gene function, lower fitness, or cause disease. The sources also stress that mutation is hard to study because it is noisy, varies across species and conditions, and is mixed up with the effects of natural selection.
[2] pmc.ncbi.nlm.nih.gov · articles · PMC4563715Mutation—The Engine of Evolution: Studying Mutation and Its ... [3] Mechanism
SEE THE IDEA
From DNA change to evolutionary effect
A base change, insertion, deletion, duplication, or inversion alters genetic sequence.
Replication error, repair error, molecular decay, or a mutagen creates the change.
Changes may be random, clustered, or enriched near a break site.
The change may help, harm, or do nothing, and selection then shapes its fate.
Sequence change is produced by a mechanism, shows a genomic pattern, and may affect fitness and evolution.
Mutation links a DNA change to where it appears and what it can do in a population.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
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4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.