Dividing faster doesn't make a new kind of cell
- The idea
- Predict
- See it
- Why
- Check
The idea
“A cell that divides faster or grows more becomes a different kind of cell.”
Embryos are full of cells dividing at different speeds that end up as different tissues, so it's easy to link the two.
The short version
The mistake: A cell that divides faster or grows more becomes a different kind of cell.
What's actually true: A cell's type depends on which genes it expresses. Division rate changes how many cells you get.
- Mitosis gives each daughter cell the same genome. Your nerve and muscle cells carry the same genes.
- What differs is gene expression, which genes a cell transcribes. Transcription factors switch on whole sets of genes, and that set decides the cell's type.
- Division rate sets how many cells a tissue gets. Skin stem cells divide all the time and still make only skin cells.
On the exam: Cell type comes from which genes are switched on. Dividing faster only makes more cells.