The meaning of genetic “words” is manifested when the information encapsulated in them turns into a protein: first, a RNA copy descends from the gene, which is then read by protein-synthesizing machines that assemble the protein molecule exactly according to what is written in RNA (RNA synthesis is called transcription, protein synthesis – translation).
True, it is worth remembering two things. First, the genetic “words with meaning” are interspersed with pieces of some nonsense – between the genes there are DNA sequences that do not encode any proteins. Secondly, the “words” themselves-genes consist of fragments, which are called introns and exons.
Exons are “semantic” fragments, but introns do not have any information for protein synthesis. Imagine the word “cow” in which there is some meaningless sequence of letters between the syllable “co-” (one exon) and the remainder of “-ro” (second exon), and to read the “cow” we need throw this nonsense away. Something similar happens at the molecular level: when a gene in DNA synthesizes its RNA copy, it initially includes everything as it is, and introns, and exons. But then RNA passes through a procedure called splicing: special enzymes cut out introns and connect exons into a meaningful word.
And non-coding DNA between the genes, and introns at one time called garbage DNA. Various hypotheses have been put forward about how and why it appeared at all in the course of evolution, especially in such a quantity (introns, for example, make up 90% of the gene sequences). But recently there is more and more data, because of which the word “garbage” should be quoted. It turns out that such DNA can influence the activity of genes: it contains regulatory regions that suppress or stimulate the synthesis of RNA copies in “meaningful” regions of DNA, and in the “junk” DNA, various regulatory RNAs are often encoded-they do not carry a protein information, but again serve as a powerful tool for regulating genetic activity.
As for the intron “garbage”, it has been found over time that if the gene is completely removed these useless sequences, then the gene will become inactive. Introns can be compared with volume controllers: let the gene formally work, but it depends on introns how intensively it will be transcribed, how many copies of RNA will be made on the gene.