I asked this in Chemistry and it was suggested to ask it here. I wondered how the genome, which afaik does not contain iron or calcium as "reference" copies, nonetheless produces an organism that uses certain elements. If it create proteins which bind preferentially to iron or calcium, how then are such elements routed to sites where they can be bound? Are there proteins in addition to those which bind to elements that are responsible for routing? I should mention that I am a software developer and imagine mechanisms analogous to computer code.
A wikipedia source gives you general informations and precise details about the locations and methods of absorption and distribution. Reading the page is well recommended, I will add the quote to save others time:
Like most mineral nutrients, the majority of the iron absorbed from digested food or supplements is absorbed in the duodenum by enterocytes of the duodenal lining. These cells have special molecules that allow them to move iron into the body. To be absorbed, dietary iron can be absorbed as part of a protein such as heme protein or iron must be in its ferrous Fe2+ form.
A ferric reductase enzyme on the enterocytes’ brush border, duodenal cytochrome B (Dcytb), reduces ferric Fe3+ to Fe2+.
A protein called divalent metal transporter 1 (DMT1), which can transport several divalent metals across the plasma membrane, then transports iron across the enterocyte’s cell membrane into the cell.
These intestinal lining cells can then either store the iron as ferritin, which is accomplished by Fe3+ binding to apoferritin (in which case the iron will leave the body when the cell dies and is sloughed off into feces), or the cell can release it into the body via the only known iron exporter in mammals, ferroportin.
Hephaestin, a ferroxidase that can oxidize Fe2+ to Fe3+ and is found mainly in the small intestine, helps ferroportin transfer iron across the basolateral end of the intestine cells. In contrast, ferroportin is post-translationally repressed by hepcidin, a 25-amino acid peptide hormone.
The body regulates iron levels by regulating each of these steps. For instance, enterocytes synthesize more Dcytb, DMT1 and ferroportin in response to iron deficiency anemia. Iron absorption from diet is enhanced in the presence of vitamin C and diminished by excess calcium, zinc, or manganese.