POLIMERAZAS
The DNA polymerizes polymerizes
The DNA is an enzyme that catalyzes the synthesis of DNA from deoxyribonucleotides and a DNA template or mold.
After the action of DNA polymerization and once I have removed and added about a 10 bases, the enzyme involved ligaza DNA, which connects the free ends of newly formed fragment with the rest of the chain, thereby recovering
normal DNA structure property of polymerizing DNA to replicate DNA strands are used for chain reaction polymerization, known as PCR for its acronym in English, for a large number of copies of a particular DNA fragment, amplifying for research purposes
polymerized DNA (enzyme that makes a polymer of DNA ") plays a critical role in the synthesis of new DNA chains. In each replication fork, DNA polymerization and other enzymes synthesize two new strands of DNA that are complementary to the 2 parental chains. During this process, recognizes polymerized DNA nucleotide base unpaired parental chain and combines with free nucleotide that has the correct complementary base. Next, the polymerized DNA catalyzes the formation of new covalent bonds linking the nucleotide phosphate free incoming nucleotide sugar previously added to the growing daughter strand. Thus, the DNA synthesizes polymerized sugar-phosphate backbone of the daughter strand RNA polymerization
The
The RNA-resin are a set of proteins as an enzyme capable of polymerizing ribonucleotides to synthesize RNA from a DNA sequence that serves as pattern or mold. The RNA polymerization is the most important involved in the synthesis of messenger RNA or transcription DNA. RNA polymerization
The soluble enzyme is known as the largest measuring about 100 angstroms in diameter and is visible in electron micrographs, showing together with the promoter DNA. Features
The chemical reaction catalyzed RNA polymerization is the union of ribonucleotide triphosphate, adenine triphosphate (ATP), uracil triphosphate (UTP), guanine triphosphate (GTP) and cytosine triphosphate (CTP), releasing the phosphate groups.
addition polymerization of ribonucleotide triphosphate, RNA polymerization has other functions as
• Recoconer and bind to specific sites or promoters of the molecule RNA. • Unroll partially
template DNA molecule due to its intrinsic helicaza activity.
• Synthesize an RNA primer for subsequent elongation.
• Completion of the chain. The RNA catalyzes
consecutively polymerized chain elongation of RNA, while winds and unwinds the double-stranded DNA, and transcription ends after copying the gene. Structure
This complexity of functions is manifested in its quaternary structure, as well as DNA polymerization, is formed by several subunits that form the holoenzyme, which together with accessory proteins form a complex machine transcription or protein carrying out the synthesis of RNA.
Some isolated subunits of the RNA are catalytically polymerized functional, while others can only be detected when the transcription complex is fully assembled.
transcription complexes from different organisms have a variable composition, but essentially all catalyze the same type of reactions. Given this coincidence, the study of the transcription process is modeled after the reactions catalyzed by the transcription complex of Escherichia coli bacteria, although it differs in the assembly of eukaryotic cells, they act similarly.
The RNA polymerization was discovered while messenger RNA in 1960 by Samuel Weiss and researchers of different laboratories Hurwits Jerard. Polymerized RNA in prokaryotes
In prokaryotes, the same enzyme catalyzes the synthesis of all types of RNA: mRNA, rRNA and tRNA.
The prokaryotic RNA polymerizes in a large molecule. It consists of five subunits of approximately 410 kilodaltons α2ββ'ω, with two identical α units, which binds to DNA non-specifically to catalyze the synthesis of RNA. To join a specific promoter regions, the holoenzyme requires the σ factor that greatly reduces the affinity for nonspecific DNA regions, increasing the specificity by regions promoter to form the holoenzyme α2ββ'σω five subunits (~ 480 kDa). The structure of the RNA polymerization has a groove of 55 Å in length and width 25 Å. This slot allows the passage of the DNA double helix is \u200b\u200b20 Å. The length of 55 Å can accept the sequence of 16 nucleotides.
All enzyme units are working together to carry out the transcription reactions. The β subunit 'involved in the binding of DNA, the β subunit contains part of the active site and the σ subunit is mainly involved in the initiation of transcription and dissociate from the rest of the enzyme after the initiation of transcription.
The polymerized RNA prokaryotic organisms operate in a similar manner, although some protein subunit differs in its composition. Eukaryotic RNA polymerization
eukaryotic cells have different types of RNA polymerization.
• RNA polymerization I: synthesizes ribosomal RNA precursors.
• RNA polymerization II: synthesizes messenger RNA precursors. This polymerization is the most studied, and transcription factors are required to be a DNA promoters. • RNA polymerization
III synthesizes transfer RNA, 5S ribosomal RNA and other small RNAs found in the cell nucleus and cytoplasm.
• Other types of RNA are polymerized in the mitochondria and chloroplast and the nucleus of the ribosome.
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