Ribosomal RNA

The ribosomal RNA (of rRNA), a component of the ribosomal RNA, which is essential for protein synthesis in all organisms. It consists primarily of a material within the ribosome are OK. Protein and 40% rRNA of 60 percent by weight. Ribozymes, protein and more than 50 major rRNAs of two is included. Respectively, SSU rRNAs and LSU, are located small, the large ribosomal subunit. The LSU rRNA acts as a ribozyme that catalyzes the formation of peptide bonds. They are of ancient origin, because it has been found in the form of all known life, is used to rRNA sequences makes a connection between evolutionary species widely.

Ribosomal RNA

Ribosomal RNA to form a (SSU) of two subunits, large subunit and small subunit (LSU). The mRNA, is sandwiched between the large and small subunits, catalyzed the formation of a peptide bond between amino acids of the two in the rRNAs ribozymes. The ribosome, the site known as the binding of one 3,, P, and have an FI bind to (mRNA that was associated with the amino acid) aminoacyl-tRNA in one place within the ribosome. Ester bond of the peptidyl-tRNA containing the last amino acid of the growing chain to amino aminoacyl-tRNA with the new amino acids (NH 2) group to form a new peptide bond (contained in the P site) I will attack. This reaction is catalyzed by peptidyl. MRNA held in the last amino acid is transferred to the site E, aminoacyl tRNA are those which are used that have peptidyl-tRNA. A single mRNA can be translated simultaneously in more than one ribosome.

In contrast, to have multiple copies of rRNA genes are arranged in tandem repeats in general and eukaryotes, in humans, repetition of about 300 to 400 times, five groups (chromosomes 13, 14 and 15 , is divided into 21, 22). For the transfer of action and the structure of the rRNA gene cluster, (Please note that it seems to mean that the term is included in the DNA that ribosome is not the case) “ribosomal DNA” in general it is called. It is a small ribosomal subunit of the 18S rRNA of most eukaryotic, are included (28S and 5S in 25S mammals plant, and 5.8S, rRNAs) are three types of rRNA of the large subunit.

(In the 28S, 5S subunit 5.8S, and 18S) I have four types of cytoplasmic rRNA molecules and rRNA (16S and 12S) mitochondria of two mammalian cells. Of the 28S, 18S rRNAs and 5.8S are encoded in (45S) single transcription unit that are separated by two internal transcribed spacer. Organized (30-40 in each iteration) groups of five and 22 chromosomes 13,14,15,21, in the 45S rDNA. The 5S, which is transcribed in RNA polymerase I, (pseudogenes distributed and many ~ 200-300 true 5S gene) tandem array, they can occur up to chromosome 1q41-42. 5S rRNA gene is transcribed by RNA polymerase III. Tertiary structure (SSU of rRNA) small subunit ribosomal RNA is determined by X-ray crystallography. 5 ‘center, 3’, small large 3 ‘region – secondary structure of SSU rRNA contains four fields. Model of the secondary structure 5 ‘region (nucleotides 500-800) are shown. Translation is the net effect of the protein synthesized by the ribosome (for mRNA) copy of the template DNA in the nucleus. the sequence of base pairs upstream of the start codon of the mRNA in one of the components of the ribosome complementary (for 16S rRNA).

It contains the 16S rRNA of the small 30S ribosomal subunit in prokaryotes. (Of 23S rRNAs and 5S) rRNA the two species are included in the large 50S ribosomal subunit. 16S of bacteria, usually, 5S rRNA gene and 23S are organized as co-operon transcription. (For example, a Escherichia coli, and 7) may have more than one copy of the operon dispersed in the genome can be present. The archaea, multiple copies of the operon or operon of rDNA is included. ‘The end of the 16S rRNA of (internal ribosome) in the sequence of the 5’ end of the mRNA 3 called Shine sequence.

It appears as a dense region in the core, ribosomal RNA molecules are synthesized in specialized regions of the cell nucleus, called the nucleolus, including genes encoding ribosomal RNA. This is the location of the ribosomal subunit of ribosomal protein and rRNA again. Are synthesized in the cytoplasm, ribosomal protein was transported to the nucleus of the nodes in the nucleus. Subunit, went back to the cytoplasm for final assembly.

That it forms a secondary structure extensive RRNAs, play an active role in the identification of sites stored in tRNA and mRNA. In (organisms with nuclei of well-defined), may be present in a single cell eukaryotic ribosomes anywhere from more than 10 million and 50 to set the rRNA genes. In contrast to (organisms without a non-core) prokaryotes, and a group with less ribosomes per cell, and typical rRNA gene. For example, bacteria in E. coli, a copy of the rRNA genes to synthesize about 15,000 ribosomes per cell 7.

There is a difference between the radical in prokaryotic bacteria and archaea in the region. Except that it is apparent, these differences are shown in the rRNA sequence composition of the lipids used, cell walls, and metabolic pathways and different. Because it is the rRNA of eukaryotes, RRNAs they of archaea and bacteria, are different as each other. Because it suggests a branch from a common ancestor just before the eukaryotic cells have been developed line of archaea and bacteria, this information is important in understanding the origin of the evolution of these organisms.

The bacteria of the gene was most beneficial to investigate the relevance of evolution, in units Svedberg, the one of (16S, refers to the percentage of precipitation the RNA component of the small subunit ribosomal 16S rRNA gene, bacterial The RNA molecules in the centrifugal force field is a DNA sequence coding). Form that is present in all bacteria of the 16S rRNA gene, including those of eukaryotes, are associated with all cells. Sequence analysis from many organisms, the 16S rRNA gene, that by certain parts of the molecule to distinguish between different species of the same genus in rapidly and undergo genetic changes revealed. The other items, it is possible to distinguish the classification level much wider, it changes very slowly.