What Is a Genetic Mutation?

Science · Ecosystems & Habitats · ages 12-14

Name ______________________ Date ____________

Which of these is a mutagen, something that can cause a mutation?
- Drinking water
- Radiation from the sun
- Sleeping eight hours
What is a genetic mutation?
- A random change in a DNA sequence
- A muscle that helps a cell move
- A type of chromosome found only in plants
True or false: most mutations that happen are harmful to the organism.
Circle one: True False
A person sunbathes for hours without sunscreen, and UV light damages a gene in their skin cells. What caused this mutation?
- Radiation
- A copying error
- Natural selection
A cell copies its DNA before dividing, and one letter gets copied wrong by accident. What just happened?
- A mutation caused by radiation
- Nothing, since no chemical was involved
- A mutation caused by a copying error
Without mutations ever occurring, where would new versions of a gene come from?
- Copying itself perfectly every time
- Nowhere, mutations are the original source of new genetic variation
- Only from natural selection
Two unrelated beetles each develop a new mutation in the same gene, but the two changes look different from each other. What does this best show about mutations?
- Mutations are random, so different copying errors or mutagens produce different results
- That gene cannot be mutated a second time
- Mutations always produce the exact same change
A student says: 'A mutation that helps an animal survive will just disappear after one generation.' What is wrong with this claim?
- Helpful mutations only occur in plants
- Mutations can only be caused by radiation
- A helpful mutation can be favored by natural selection and become more common over time

Answer key

For grown-ups. Fold this page away before handing over the rest.

What Is a Genetic Mutation? W1-mt_rOqo-8GeKt-s1

Radiation from the sun · Radiation, certain chemicals, and copying errors can all damage or change DNA.
A random change in a DNA sequence · A mutation is any change to the sequence of DNA, big or small.
False · Most mutations don't change how the organism works at all. We call these neutral.
Radiation · UV radiation from the sun is a mutagen that can damage DNA in skin cells.
A mutation caused by a copying error · Errors during DNA copying are one of the most common causes of mutation.
Nowhere, mutations are the original source of new genetic variation · Every new version of a gene starts out as a mutation. Without mutation, there is no new variation to work with.
Mutations are random, so different copying errors or mutagens produce different results · Because mutations are random events, even the same gene can end up changed in many different ways in different individuals.
A helpful mutation can be favored by natural selection and become more common over time · When a mutation helps survival or reproduction, natural selection can favor it, so it spreads through the population over generations instead of vanishing.