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.
I’ll focus on a side question, that I’m more prepared to answer.
At the end of the day, proteins are biiiiig arse molecules. Mostly composed of carbon, hydrogen, oxygen, and nitrogen. For example, here’s a protein called “myoglobin”, that carries oxygen within your blood:
Blue = nitrogen, red = oxygen, grey = carbon, white = hydrogen, salmon = iron, yellow = sulphur. Disregard the mix of sticks and balls in the model, they’re both representing atoms.
If you pay close attention to the model, you’ll notice a repetitive pattern: 1) nitrogen, 2) carbon connected to some large junk, 3) carbon connected to a “dangling” oxygen. That is not just in the myoglobin, but in all proteins.
If you flattened that pattern and removed the hydrogens (to simplify it), you’d get something like this:
That happens because the bodies of living beings don’t build those huge molecules out of nowhere; they do it with smaller molecules called “aminoacids”. That pattern there is the amide group, you could see it as the “solder” between aminoacids.
Here’s the representation of a few “free” aminoacids:
The fun part is that R, the “side chain”. I called it “junk” but it’s actually a big deal - because it’s what gives each protein a different shape and property. For example, it’s thanks to that junk that the myoglobin has a specific shape, that forms a “ring” of nitrogens, just at the right size to host an iron cation, but still leaves one of the sides of the iron cation free - so it could connect to something else. (Hopefully diatomic oxygen. As in, it’s how myoglobin transports that oxygen within your body. But if you get poisoned with carbon monoxide or cyanide, it gets stuck there, and it’s hard to take it off so the protein stops transporting oxygen.)
The R side chains are not referred to as radicals. R- is common in organic chemistry and refers to a part of a molecule not shown for some reason. Generally because it’s not the focus in the specific figure. Generally you’ll have a R = (whatever combination of atoms) defined below.
Radicals are a specific atom with an unpaired valence electron. Sometimes also called “free radicals”.
Edit, here’s an example of a non-amino acid use of R:
Myoglobin is in the muscles. Hemogoblin is in the blood and is essentially 4 myoglobin molecules that can combine into one hemoglobin. IIRC, the combination of the 4 makes it easier to switch between accepting and donating oxygen, where myoglobin is better just at the taking oxygen.