Genetic Mutation
Explain genetic mutation as a random change in DNA sequence, describe causes of mutation (e.g. radiation, chemicals, copying errors), and explain that most mutations are neutral, some harmful, and a few beneficial
What a learner can do afterwards
- Defines mutation as a change to DNA sequence
- Names at least two things that can cause mutations (mutagens)
- Explains that mutations are the original source of all genetic variation
- Explains that beneficial mutations can be selected for by natural selection
The lesson
You already know your genes are made of DNA, a code written in a chemical alphabet. A mutation is a random change in that code: one letter gets swapped, added, or dropped by accident.
Mutations happen a few ways. Cells copy their DNA every time they divide, and copying is nearly perfect but not flawless, so a wrong letter slips in sometimes. Radiation, like the UV light in sunlight, can also damage DNA. So can certain chemicals, like the ones in cigarette smoke.
A beetle is born with a mutation that makes its shell slightly darker. On bright sandy ground, this makes no real difference, so the mutation is neutral. But on a shaded forest floor, the darker beetle is harder for birds to spot. That same mutation just became useful.
Most mutations don't change much at all, we call these neutral. A few cause harm. But every so often, one helps an organism survive or reproduce, and natural selection can favor it. That's why mutations are the raw material behind all genetic variation.
A mutation is a random change in DNA caused by copying errors, radiation, or chemicals, and while most are neutral, the rare helpful one can spread through a population.
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8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.