Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase, is an enzyme that catalyzes the formation of deoxyribonucleotides from ribonucleotides.
Ribonucleic acid (RNA) is a polymeric molecule implicated in various biological roles in coding, decoding, regulation, and expression of genes. RNA and DNA are nucleic acids, and, along with proteins and carbohydrates, constitute the three major macromolecules essential for all known forms of life. Synthesis of RNA is usually catalyzed by an enzyme— RNA polymerase —using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found upstream of a gene). Deoxyribonucleotides in turn are used in the synthesis of DNA. The reaction catalyzed by RNR is strictly conserved in all living organisms. Furthermore RNR plays a critical role in regulating the total rate of DNA synthesis so that DNA to cell mass is maintained at a constant ratio during cell division and DNA repair. A somewhat unusual feature of the RNR enzyme is that it catalyzes a reaction that proceeds via a free radical mechanism of action. Cellular organisms use messenger RNA (mRNA) to convey genetic information (using the letters G, U, A, and C to denote the nitrogenous bases guanine, uracil, adenine, and cytosine) that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome. Synthesis of RNA is usually catalyzed by an enzyme— RNA polymerase —using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found upstream of a gene). Messenger RNA (mRNA) is the RNA that carries information from DNA to the ribosome, the sites of protein synthesis (translation) in the cell. The coding sequence of the mRNA determines the amino acid sequence in the protein that is produced. Synthesis of RNA is usually catalyzed by an enzyme— RNA polymerase —using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found upstream of a gene). The MT-RNR1 gene provides instructions for making a particular type of RNA, a molecule that is a chemical cousin of DNA. This type of RNA, known as ribosomal RNA (rRNA), is involved in the assembly of proteins within cells. The MT-RNR1 gene provides instructions for a specific form of ribosomal RNA called 12S RNA, which is present only in cellular structures called mitochondria. These structures convert energy from food into a form that cells can use RNA–in this role–is the “DNA photocopy” of the cell. When the cell needs to produce a certain protein, it activates the protein’s gene –the portion of DNA that codes for that protein–and produces multiple copies of that piece of DNA in the form of messenger RNA, or mRNA. A central tenet of molecular biology states that the flow of genetic information in a cell is from DNA through RNA to proteins: “DNA makes RNA makes protein”. Proteins are the workhorses of the cell; they play leading roles in the cell as enzymes, as structural components, and in cell signaling, to name just a few. When the cell needs to produce a certain protein, it activates the protein’s gene –the portion of DNA that codes for that protein–and produces multiple copies of that piece of DNA in the form of messenger RNA, or mRNA. The iron-dependent enzyme, ribonucleotide reductase (RNR), is essential for DNA synthesis. Class I RNR enzymes are constructed from large RNR1 and small RNR2 subunits which associate to form an active heterodimeric tetramer. Furthermore RNR plays a critical role in regulating the total rate of DNA synthesis so that DNA to cell mass is maintained at a constant ratio during cell division and DNA repair. A somewhat unusual feature of the RNR enzyme is that it catalyzes a reaction that proceeds via a free radical mechanism of action. Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase, is an enzyme that catalyzes the formation of deoxyribonucleotides from ribonucleotides. Furthermore RNR plays a critical role in regulating the total rate of DNA synthesis so that DNA to cell mass is maintained at a constant ratio during cell division and DNA repair. A somewhat unusual feature of the RNR enzyme is that it catalyzes a reaction that proceeds via a free radical mechanism of action.
https://en.wikipedia.org/wiki/RNA https://en.wikipedia.org/wiki/Ribonucleotide_reductase https://en.wikipedia.org/wiki/RNA https://en.wikipedia.org/wiki/RNA http://ghr.nlm.nih.gov/gene/MT-RNR1 http://www.rnasociety.org/about/what-is-rna/ http://www.rnasociety.org/about/what-is-rna/ https://en.wikipedia.org/wiki/Ribonucleotide_reductase https://en.wikipedia.org/wiki/Ribonucleotide_reductase
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