For example, in May 2020, the American pharmaceutical company Editas Medicine reported that it had used CRISPR / Cas9 to cure a form of congenital blindness. This discovery made it clear that by editing the genome, you can “cut out” many genetic diseases. Our DNA is arranged as such: if it lacks something, it copies it from the next cell, and in the next it is possible to “enclose” what is necessary. ![]() There are some ways to prompt the body how to “stitch” a strand of DNA without a defect. And instead of the DNA fragment, the virus can encode any other, such as a defective part of the genome that causes a genetic disease. The Cas9 protein binds to this RNA, cutting out the necessary (or “problematic”) DNA fragment. The editing happens as follows: in the laboratory, CRISPR RNA is created with the required spacer. It became the subject of research which by 2012 had shown that the immune mechanism of bacteria could edit the human genome. And there is, for example, the Cas9 protein: in this case, all the work is undertaken by one powerful protein. In some, stages of the “special operation” are responsible for individual Cas-proteins, which form a complex system. Photos of Pawel Czerwinski used in the collage The Cas9 ProteinĬRISPR systems are different. In addition, spacers with data on viruses that have not attacked the cell for a long time are subsequently erased from the DNA. Viruses mutate, and the CRISPR RNA from proteins can stop recognizing them. The Cas-protein carefully “cuts” the DNA sequence of the virus, thus killing two birds with one stone - it destroys the virus and, at the same time, collects new spacers, if necessary. When a virus invades, a guide is formed - an RNA molecule that carries in itself information about viruses and, together with Cas proteins, performs the function of finding and destroying them. Spacers in the CRISPR sequence are DNA fragments of viruses familiar to the cell, something like a data folder. It was found to match the DNA of some bacteriophages - viruses that infect bacteria - and that CRISPR is a bacterial immune system with a clear system of teamwork. ![]() The breakthrough came in 2005, when several laboratories decided to compare the enigmatic CRISPR with already known DNA sequences. However, for a long time no one could understand what that meant. In 2002, it was discovered that these “repeats” were accompanied by specific Cas proteins. Spanish scientist Francisco Mohica described these sequences as such: “Short palindrome repetitions, regularly arranged in groups.” It came to be known as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) was released. The detected sequences looked strange - repetitive segments which were separated by different sections. Bacteria usually have a simpler and “laconic” strand of DNA. They were surprised to discover a “non-coding sequence” that only humans have. In 1987, Japanese scientists were studying the DNA of Escherichia coli, a common intestinal strain that causes an acute infection. Some of them perform various procedural and technical functions, but the role of most of these “statements” remains unknown. ![]() In addition to genes in DNA, there are so-called “non-coding sequences”, which do not contain any instructions or information. Yes, in the simplified version, this is how the key mechanism of our life occurs. Then the RNA leaves the nucleus, and the synthesis of the necessary proteins begins. To take information from the “database”, a special enzyme creates ribonucleic acid (RNA) in the cell nucleus, which copies the necessary genetic “instructions” from DNA. If we imagine that the genome is a very long text, and the nucleotides are letters, then the gene is a small part of the text, a complete statement.įor example, a gene encoding insulin production consists of 60 nucleotide pairs. The set of human genes is a genome consisting of 46 chromosomes. A gene is a piece of DNA with a specific nucleotide sequence. The DNA strand consists of nucleotide units. This is something like instructions for building our body to the infinitesimal detail. DNA is a database where our genetic information is stored. There are deoxyribonucleic acid (DNA) molecules in the nucleus of our cells.
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