The DNA is considered the holy grail of genetics and evolutionary biology alike. Complex life on this planet is unthinkable without DNA as the carrier of genetic information.
DNA is the abbreviation for "Deoxyribonucleic acid", in German Deoxyribonucleic acid (DNA). For biochemists, this designation already says the most important things about their structure, but normally a few explanatory words are required.
DNA is a complex molecule made up of two almost identical single strands, in which "almost" the origin of genetic diversity is hidden. Each strand consists of a stable deoxyribose phosphoric acid chain to which various organic bases are attached. Both strands are intertwined in a double helix and thus form the DNA.
But that's not all: extremely long DNA threads are organized into a large overall complex, the chromosomes, of which humans have 23 pairs in the nuclei of all body cells. These chromosomes contain, encoded in the DNA, all the genetic information (genes) that make every living being an individual.
Every cell has a specific purpose in the organism. What this consists of can be determined by ribosomes located in the cell nucleus DNA read off. But how exactly does this fundamental cell construction kit work?
The key to understanding molecular DNA genetics lies in the conjugated base pairs adenine, thymine, guanine, and cytosine. These are linked to the DNA in a precisely defined sequence, similar to an encrypted code. The DNA is converted into similar mRNA so that a ribosome can traverse it. This records the code that supplies the ribosome with the sequence of amino acids.
The ribosome produces the corresponding amino acids and uses them to form characteristic proteins that ultimately enable cell functionality. This is how the abstract DNA becomes tangible cell building blocks. Every human cell can only survive a limited time, so that cells and with them the DNA have to multiply. Similar to bacteria, this happens through cell division. The DNA is broken down into its single strands by helicase. After separation, this enzyme uses both strands as separate matrices and re-creates the missing opposite strand so that two identical DNA molecule chains are created.
The following two extrapolations show how unimaginably huge the DNA information density is: A single gram of DNA has a data volume of 700 terabytes. In order to recreate all the people on earth, a teaspoon just needs 0.3% DNA. And if you wanted to string together the entire DNA of a single person, you would have to travel to the sun and back 500 times.
The DNA is exposed to a wide variety of disturbances over the years. These range from ingesting cell-changing substances such as burned meat or tobacco consumption to extreme heat and UV radiation. Last but not least, DNA changes can also occur through faulty metabolic processes.
Various biochemical repair and sorting mechanisms exist so that the valuable information is retained for the life of the cell. But every now and then, especially with age, cell regeneration can fail and DNA can be altered. Individual bases can be exchanged or removed, entire areas illegible, the strand cut in half, in short: the genetic code is now wrong. If the cell is still able to divide, a defective cell can over time lead to an accumulation of diseased cells.
If such DNA mutations are expressly desired in the sense of evolutionary theory, they usually mean the diagnosis of cancer in all its facets for the specific patient. But sickle cell anemia, albinism, cystic fibrosis or hemophilia can also develop through DNA mutations in addition to heredity. Certain types of viruses represent a particularly refined form of life that makes use of foreign DNA.
They cannot reproduce on their own and for this purpose infiltrate other cells. In these, they replace the DNA with their own and are thus reproduced by the host cell in a pathogenic form. Dangerous viral diseases and even death can result.