Moved isn't the same as made
- The idea
- Predict
- See it
- Why
- Check
The idea
“There's more of the protein in the membrane now, so the cell made more.”
Cells do make new proteins when they get a signal, so a higher count in the membrane looks like more was made. That count only tells you what's in one place, though.
The short version
The mistake: There's more of the protein in the membrane now, so the cell made more.
What's actually true: A protein can move to a new part of the cell while its total stays the same. Check the whole-cell total first.
- Cells often answer a signal within minutes by moving proteins they already have.
- Making new protein is slower, so a big jump in one place within minutes is usually a move.
- Where a protein sits decides its job. GLUT4 lets glucose in only when it's in the membrane, and a transcription factor reaches DNA only in the nucleus.
On the exam: Check the total before you say more was made. If one place gains what another loses, it moved.