How does DNA decide the shape of the body?
How does DNA decide the shape of the body?
I know that DNA encodes proteins. Truthfully, everything besides that (including 'what are proteins') mostly wooshes over my head, but that's not relevant because whenever I search this question I never even find it addressed anywhere.
The human body has, among other things, two hands each with five fingers, with a very particular bone structure. How are things like that encoded in DNA, and by what mechanisms does that DNA cause these features to be built the way they are? What makes two people have a different nose shape? Nearly everyone in my family has a mole on the left side of their face, how does that come about from DNA?
I'm sure there are many steps involved, but I don't see how we go from creating proteins to reproducibly building a full organism with all the organs in the right places and the right shapes. Whenever I try to look this up, all of these intermediate steps are missing, so it basically seems like magic.
As I said, any explanation will most likely go over my head and I won't be able to understand it fully, but I at least want to see an explanation. I'll do my best to understand it of course.
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Genes!
We all start as a single cell that gets fertilized by a sperm. That single cell creates a copy of itself to become 2 cells. The 2 do the same to become 4, 4 become 8, and so on. At a certain point, you have enough cells to start differentiating and giving the cells a “job”. Your cells know where they are in your body by communicating with the cells around it, and that influences what job the cell should have.
Genes are a sequence of DNA, and certain genes serve as a “recipe” for proteins which do a lot of important work in the cell. The cell’s job determines which genes are used and therefore which proteins are made. The genes provide the information needed for the cells to form a certain way (look like a nose) and function a certain way (behave like a nose) and proteins help facilitate that.
Two people have different noses because they have different genes (different instructions for how it should look). Your family has a mole on the left side of their face because that gene continues to be passed down with each generation and instructing the cells in the face to form a mole.
I tried to simplify as much as I could without losing the integrity of the information. I hope this makes sense and is helpful!