Mutations
Introduced| English |
|---|
| mutation/mjuːˈteɪʃn/ |
| substitution/ˌsʌbstɪˈtjuːʃn/ |
| insertion/ɪnˈsɜːʃn/ |
| deletion/dɪˈliːʃn/ |
| mutagen/ˈmjuːtədʒn/ |
Mistakes in the code
- Copying billions of DNA bases is astonishingly accurate — but not perfect.
- Once in a while, a base gets changed.
- Such a change to the DNA is called a mutation.
- Mutations can be harmful, harmless, or, rarely, a lucky improvement.
What a mutation is
- A mutation 突变 is a change in the DNA base sequence.
- Because the sequence codes for proteins, a mutation can change a protein.
- A changed protein may work differently — or not at all.
- Even a single base swapped can matter.
A mutation is…
A mutation is a change in the DNA sequence, which can change the protein a gene makes.
Types of mutation
- A substitution 替换 swaps one base for another.
- An insertion 插入 adds an extra base into the sequence.
- A deletion 缺失 removes a base.
- Insertions and deletions shift the reading frame, often disrupting the whole protein.
A substitution mutation is when…
A substitution swaps one base for another; insertions and deletions add or remove bases.
Effects and causes
- Many mutations have no effect at all — they are neutral.
- Some are harmful; a rare few are beneficial.
- Beneficial mutations provide the variation that drives evolution.
- A mutagen 诱变剂 — UV light, radiation, or some chemicals — raises the mutation rate.
Helpful, harmful, or neutral?
Sort each mutation by its effect - many do nothing, some harm, and a few help.
A factor that increases the mutation rate, like UV light, is a ____.
A mutagen — UV light, radiation, or certain chemicals — makes mutations more likely.
Some mutations are neutral or even beneficial, not just harmful.
Many mutations have no effect; a few are helpful — these provide the variation that drives evolution.
Select all true statements about mutations.
Not every mutation is harmful — many are neutral and some are beneficial. The other three are correct.
Not every mutation is bad. Most are neutral, some are harmful, and a rare few are beneficial — and those helpful changes are the raw material of evolution. Do not assume "mutation" always means damage.
One base, a big difference:
- Sickle-cell disease comes from a single substitution in the haemoglobin gene.
- That one changed base makes a faulty haemoglobin, harming red blood cells.
- Yet the same allele also protects against malaria — the very same mutation can be both harmful and helpful.
A mutation is a change in the DNA base sequence. Types include substitution (swap a base), insertion (add one), and deletion (remove one). Mutations can be harmful, neutral, or beneficial, and a mutagen raises their rate. Beneficial mutations supply the variation for evolution.