Ribosomal ribonucleic acid structure

The chemical polymerization of even a moderately sized protein of a hundred amino acids in the laboratory is extremely laborious, and the yields of active product can often be low to zero (Kent and Parker, 1988). Cells accomplish this task by using an intricate mechanism which involves catalytic machinery composed of proteins, nucleic acids and their complexes, and synthesize polypeptide chains that are composed of hundreds of amino acids. This process is depicted in Fig. 2.4, and is described in the sections below. The basic components of the cellular protein synthesis apparatus, in all known biological systems, are ribosomes, which are aggregate structures containing over fifty distinct proteins, and three distinct molecules of nucleic acid known as ribosomal ribonucleic acid (ribosomal RNA or rRNA). The amino acids are brought to the ribosomes, the assembly bench , by an RNA molecule known appropriately as transfer RNA . Each of the twenty amino acids is specifically coupled to a set of transfer RNAs (discussed below) which catalyze their incorporation into appropriate locations in the linear sequence of polypeptide chains. Several other intracellular proteins known as init iation and elongation factors a re also required for protein synthesis. 

RM Reference Material RNA ribonucleic acid (structural element of the cytoplasm and cell nucleus), consisting of D-ribose sugar, the nitrogenous bases adenine, guanine, cytosine and uracil. There are three different types transfer RNA, messenger RNA and ribosomal RNA RNAA radiochemical neutron activation analysis (post irradiation radiochemical separation)... 

In like manner, ribosomal ribonucleic acid (rRNA) and transfer ribonucleic acid (tRNA) are synthesized from their specific genes through the action of DNA-dependent RNA polymerase. And as in the case of mRNA, each of the precursor forms of these nucleotides are also processed until they reach their final forms. The rRNAs and a large variety of ribosomal proteins are assembled to form the ribosome. Ribosomes, the supramolecular structures in which protein synthesis takes place and which functionally resemble multienzyme complexes, are elaborate structures. They are attached, by a binding site on the smaller subribosomal particle, to the endoplasmic reticulum. The tRNAs that are synthesized finally become charged with specific amino acids. 

Ribonucleic acid (RNA) Molecules including messenger RNA, transfer RNA, ribosomal RNA, or small RNA. RNA serves as a template for protein synthesis and other biochemical processes of the cell. The structure of RNA is similar to that of DNA except for the base thymidine being replaced by uracil. 

The nucleus of eukaryotic cells is a very complex structure, containing various components. It is separated from the rest of the cell by two membranes named the nuclear envelope. At regular intervals, the two membranes of the nuclear envelope form pores with a diameter of around 90 nm. These pores regulate flux of macromolecules to and from the cytoplasm. Inside the nucleus is located the nucleolus, which acts to produce ribonucleic acid (RNA), which is the first step for ribosome synthesis. 

The cell body contains many structures of importance. The nucleus is usually located in the center of the cell body. It contains widely dispersed, fine chromatin material. The chromatin is composed of deoxyribonucleic acid (DNA) and its associated histone proteins. The nucleolus contains the specific portion of DNA encoding the ribonucleic acid (RNA) of future ribosomes. 

Rickets, 482,483,575,576, 582,583, 584 Rislt ratio, 908, 965-%6,968 RMR, see Resting iretabolic rate RNA (ribonucleic acid), 12 cellular function, 32 chetnical structure, 13 structure, 937 synthesis, 13,16 RNA polymerase, 33-35 RNasas, 122 Rods, 561,563-564 rRNA (ribosomal RNA), 34 Rubidium, 703... 

In deoxyribonucleic acid (DNA) the carbohydrate is 2-deoxy-D-ribose, while in ribonucleic acid (RNA) the carbohydrate residue is ribose. Three types of RNA were recognized, and they can be messenger RNA (mRNA), transfer RNA (tRNA), or ribosomal RNA (rRNA), which is the most abundant in cells. Values between 10 and 10 Dalton have been reported for the molecular weight of DNA, and the molecular weight is about 10 for rRNA, 10 for mRNA, and lOMor rRNA. The simplified structures of DNA and RNA are the following ... 

The synthesis of a protein requires the mRNA as a template containing the full sequence of codons, including the codon to terminate synthesis. The ribosomes, which orchestrate protein synthesis, read the mRNA in the 5 —>3 direction. (The 5 end has a phosphate group on the 5 -carbon atom of a ribose moiety whereas the 3 end has a phospate group on the 3 -carbon atom of ribose). Protein biosynthesis requires a transfer ribonucleic acid (tRNA) to convey an amino acid to the growing peptide chain. tRNAs are specific for each codon and contain 60-95 nucleotides, a few of which have unusual structures. The 3 end of the tRNA has the sequence... 

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