Ribonucleic acid synthesis is a prerequisite for protein synthesis. In this process, ribonucleic acids transfer genetic information from DNA to proteins. In some viruses, ribonucleic acids even represent the entire genome.
What is ribonucleic acid synthesis?
Ribonucleic acid synthesis is a prerequisite for protein synthesis. In this process, ribonucleic acids transfer genetic information from DNA to proteins. Ribonucleic acid synthesis always occurs at the DNA. There, complementary ribonucleotides are assembled into an RNA strand by an enzymatically controlled process. Ribonucleic acid (RNA) has a similar structure to deoxyribonucleic acid (DNA). It consists of nucleic bases, a sugar residue and phosphates. When put together, the three building blocks form a nucleotide. The sugar consists of a ribose. This is a pentose with five carbon atoms. The difference to DNA is that the sugar in the 2-position in the pentose ring contains a hydroxyl group instead of a hydrogen atom. The ribose is esterified with phosphoric acid at two positions. Thus, a chain with alternating ribose and phosphate units is formed. A nucleic base is glycosidically bound to the side of the ribose. Four different nucleic bases are available for the construction of RNA. These are the pyrimidine bases cytosine and uracil and the purine bases adenine and guanine. In DNA, the nitrogen base thymine is found instead of uracil. Three nucleotides in a row each form a triplet, which codes for an amino acid. The code is determined by the sequence of the nucleic bases (nitrogen bases). In contrast to DNA, RNA is single-stranded. This is caused by the hydroxyl group at the 2-position of the ribose.
Function and task
Different types of RNA are synthesized during ribonucleic acid synthesis. Unlike DNA, RNA is not used for long-term storage of genetic information, but for its transmission. Among other things, messenger RNA (mRNA) is responsible for this. It copies the genetic information from the DNA and forwards it to the ribosome, where protein synthesis takes place. The information is only temporarily stored in the RNA. After protein synthesis is complete, it is broken down again. The tRNA and the rRNA do not carry genetic information, but help build proteins at the ribosome. Other ribonucleic acids take care of gene expression. Thus, they are responsible for determining which genetic information is to be read at all. They thus also contribute to the differentiation of cells. Finally, there is RNA, which even assumes catalytic functions. Some viruses contain only RNA instead of DNA. This means that their genetic code is stored in RNA. However, RNA can only be synthesized with the help of DNA. Viruses are therefore only ever capable of living and reproducing within a host cell. During ribonucleic acid synthesis, the enzyme RNA polymerase catalyzes the formation of RNA at the DNA, resulting in the exact transfer of the genetic code. Transcription is initiated by binding of RNA polymerase to a promoter. This is a specific nucleotide sequence on the DNA. In a short DNA section, the double helix is now broken by loosening the hydrogen bond. In the process, complementary ribonucleotides attach to the corresponding bases on the codogenic strand of the DNA. With the formation of an ester bond, ribose and phosphate groups join together, forming the strand of RNA. The DNA is only opened at a short section. The already synthesized section of the RNA strand protrudes from this opening. Ribonucleic acid synthesis ends at a region of the DNA called a terminator. A stop code is located there. After reaching the stop code, the RNA polymerase detaches from the DNA and the formed RNA is released.
Diseases and disorders
Ribonucleic acid synthesis is a fundamental process, so disruption has devastating consequences for the organism. In order to synthesize proteins, there should be no major abnormalities in synthesis. However, some foreign RNA particles can reprogram the entire cell so that the body cell synthesizes only foreign RNA. This process occurs frequently and plays a major role in viral infections. Viruses cannot replicate on their own. They are always dependent on a host cell. There are both DNA viruses and pure RNA viruses.Both species invade the cell and incorporate their genetic material into the host cell’s genetic code. In the process, the cell begins to replicate only the genetic material of the viruses. The cell continues to produce viruses until it dies. The newly formed viruses invade other cells and continue their work of destruction. The RNA viruses incorporate their genetic material into DNA with the help of the enzyme reverse transcriptase. After incorporation, the synthesis of viral RNA dominates, and these viruses re-enter the next cell. RNA viruses also include retroviruses. A well-known retrovirus is the HI virus. However, retroviruses are a special case. Although they also incorporate their genetic material into the DNA via reverse transcriptase, the new viruses created in the process leave the cell without destroying it. This makes it possible for infected cells to become a constant source of viruses. However, during the production of new viruses, mutations also constantly occur, which constantly change the virus. Thus, the immune system forms antibodies against the existing viruses, but before these are destroyed, the genetic code has changed to such an extent that antibodies once formed are no longer effective. The body must constantly produce new antibodies. Thus, the immune system becomes so taxed that it loses its ability to defend against bacteria, fungi, and viruses in the long run.
