Organelles are where enzymes do their work
- The idea
- Predict
- See it
- Why
- Check
The idea
“An organelle is basically a container that holds things for the cell until they're needed.”
Diagrams draw organelles as sealed rooms with something inside, so they look like places to keep things.
The short version
The mistake: An organelle is basically a container that holds things for the cell until they're needed.
What's actually true: An organelle keeps enzymes, their targets and the right conditions together, so specific reactions happen inside it.
- A lysosome is full of hydrolases, enzymes that split big molecules into small ones by adding water.
- Pumps in its membrane spend ATP to keep the inside acidic, near pH 5. That's where these enzymes work best.
- When one lysosomal enzyme is missing, its target builds up. In Pompe disease, glycogen fills the lysosomes and muscles weaken.
- Other organelles are reaction sites too. The inner membrane of a mitochondrion holds the electron transport chain.
On the exam: Ask what an organelle's enzymes do there. Storage is rarely the answer.