Regulatory mutations change the amount of protein
- The idea
- Predict
- See it
- Why
- Check
The idea
“A mutation that changes a trait must have changed the protein's amino acids or shape.”
Most mutations you study change a codon, like the one behind sickle cell. A gene can also be turned up or down while its protein stays normal.
The short version
The mistake: A mutation that changes a trait must have changed the protein's amino acids or shape.
What's actually true: Regulatory DNA sets how much of a protein is made, and when and where. Coding DNA sets its amino acids.
- Coding DNA holds the codons. A mutation there can swap an amino acid, which may change the fold, or add an early stop codon. Some change nothing.
- Regulatory DNA, like a promoter or enhancer, is where transcription factors bind. A mutation there changes how much, when or where the gene is transcribed.
On the exam: Coding DNA changes the protein. Regulatory DNA changes how much is made, and when and where.