One gene can shape many traits
- The idea
- Predict
- See it
- Why
- Check
The idea
“Each trait needs its own gene, so traits that show up together must come from separate linked genes.”
Mendel's peas had one gene for each trait, so it's natural to expect that everywhere. Real genes often shape several traits.
The short version
The mistake: Each trait needs its own gene, so traits that show up together must come from separate linked genes.
What's actually true: One gene can affect several traits at once, which is called pleiotropy.
- A gene codes for a protein. If many tissues need that protein, or its failure sets off a chain of damage, one mutation changes many traits. That's pleiotropy.
- Linked genes are separate genes near each other on a chromosome. Crossing over sometimes splits them, so their traits can show up apart.
- One gene can even make several proteins. Alternative splicing keeps different sets of exons, so different cells can make different versions.
On the exam: Many traits traced to one mutated gene? That's pleiotropy, so you don't need extra linked genes.