How dome some cells become brain cells and others become skin cells, when the DNA in all the cells is exactly the same. In other words, if the instruction are exactly the same, how does one cell become a brain cell and another a skin cell?

Question

anonymous · Answer

PLZ  HELP

thomaster · Answer

That's caused by embryonic stem cells

anonymous · Answer

I need explaination though

thomaster · Answer

They can divide and differentiate into diverse specialized cell types like brain cells, skin cells, heart cells etc.

anonymous · Answer

Thank you!

aaronq · Answer

it's all about gene expression, only certain parts of DNA are active for a given type of cell

blues · Answer

Aaronq is correct - all cells have the same set of genes. But no cell expresses all these genes - and the subsets of genes expressed by different cells are different.

These different patterns of gene expression originate in spatial distribution of cells in a developing embryo - in some very deep way, some cells know which way is up, and start expressing different genes in response to that - and also from chemical cues from the mother. As in cells on the outside of the developing embryo can sense that, and start expressing genes differently that way.

After that initial asymmetry in gene expression is established, the cells themselves emit different chemical signals. Which essentially tells other cells to express even more different sets of genes. Enhancing the contrasts between, let's say, a developing skin cell and a developing muscle cell.

anonymous · Answer

Through cell specialization, which is controlled by multicellular organism's DNA.