Is it like precise like a computer reading data or more down to some cells just happen to react to a particular part of a DNA which starts off some process?
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DNA consists of chains of molecules called nucleotides. Each nucleotide is made of a sugar, called deoxyribose, a phosphate molecule and one of 4 different nucleobases (designated “A”, “C”, “G” and “T”. The sugar and phosphate attach together end-to-end and form the backbone of the chain: phosphate – sugar – phosphate – sugar -… The nucleobase attached to each sugar is what encodes the information in the DNA. Of the four nucleobases, there are 2 pairs that like to stick together, they are called complementary. Each DNA molecule has two chains that stick together because they have exactly complementary nucleobases at every position and coil around each other to make the familiar double-helix shape.
A cell interprets DNA by building proteins, according to the instructions encoded by the DNA. Proteins themselves are chains of molecules called amino acids, so there’s some natural analogy to DNA.
To make a protein, the DNA is first copied to a messenger molecule, called messenger RNA or mRNA. mRNA is very similar to DNA. To make the mRNA, the DNA double-helix is unwound and an enzyme called RNA polymerase binds to a specific region on the DNA that tells it where the sequence coding for the protein (galled a gene) starts. The RNA polymerase helps RNA-nucleotides floating around in the cell to bind to complementary nucleotides in the DNA and thereby form a complementary string of RNA. This RNA string is terminated where the gene ends, so only contains the information required to build the specific protein. The mRNA produced is now used to build the protein:
There are 20 different amino acids that your body strings together to build proteins, and each amino acid is coded for by a sequence of 3 nucleotides. So when the cells reads the sequence ACG it knows to use amino acid X, when it reads GTC, it uses amino acid Y. The sequence ACGGTC would tell it to string together XY in the protein. This pairing of 3 nucleobases to each amino acid is called the genetic code.
Inside your cells, there are molecules called transfer RNAs or tRNAs. They consist of 3 nucleotides and an attached amino acid, precisely that one which corresponds to the 3 nucleotides, according to the genetic code.
An enzyme-complex called the Ribosome attaches to the mRNA we produced in step 1 and lets the tRNA floating around bind to the mRNA. The tRNA is complementary to the mRNA, which in turn is complementary to the original DNA and thus the tRNA corresponds exactly to the original DNA sequence. The ribosome then takes the amino acid off the tRNA. Then the ribosome moves 3 positions over, the next tRNA attaches according to the sequence and the Ribosome takes its amino acid and attaches it to the amino acid that is already there. This repeats until the entire mRNA has been parsed and we are left with a long chain of amino acids that matches the sequence in the gene in our DNA. This is our protein.
I’m sorry for the wall of text, but this is a pretty complicated process and, in fact, in reality, it’s even more complicated.
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