A mutation can make a protein more active
- The idea
- Predict
- See it
- Why
- Check
The idea
“A mutation always damages a protein, so it works less or stops working.”
Most mutations you hear about break something. Break a protein's off switch, though, and it runs all the time.
The short version
The mistake: A mutation always damages a protein, so it works less or stops working.
What's actually true: Many mutations weaken a protein, but some lock it on or remove its off switch, so it works more than it should.
- A mutation changes a DNA sequence. In a gene, that can change the protein's shape, and the effect depends on where.
- Many mutations weaken or break a protein. That's a loss of function. Some change nothing, like a silent mutation.
- Others are a gain of function. The protein gets stuck on, or loses the part that shuts it down.
- A gain-of-function mutation in a gene that pushes division, a proto-oncogene, makes it an oncogene. Cells divide without the signal.
On the exam: A mutation can break a protein or lock it on. Ask whether the result shows too little activity or too much.