Protein synthesis messenger RNA

Ribosome A granule of protein and RNA, synthesized in the nudeolus and found in the cytoplasm of cells. Ribosomes are the main sites of protein synthesis. Messenger RNA attaches to them and there receives molecules of transfer RNA bearing amino adds. [NIH]... 

There are three major types of RNA that participate in the process of protein synthesis ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA). They are unbranched polymers of nucleotides, but differ from DNA by containing ribose instead of deoxyribose and uracil instead of thymine. rRNA is a component of the ribosomes. tRNA serves as an adaptor molecule that carries a spe dfic amino acid to the site of protein synthesis. mRNA carries genetic information from the nuclear DNA to the cytosol, where it is used as the template for protein synthesis. The process of RNA synthesis is called transcription, and its substrates are ribonucleoside triphosphates. The enzyme that synthesizes RNA is RNA polymerase, which is a multisub-irit enzyme. In prokaryotic cells, the core enzyme has four subunits—... 

RNA has a variety of functions within a cell for each function, a specific type of RNA is required. Messenger RNA (mRNA) serves as intermediaries for carrying genetic messages from the DNA to the ribosomes where protein synthesis lakes place. Ribosomal RNA (rRNA) serves both structural and functional roles in the ribosome it is diverse, both in terms of its size and structure. Transfer RNAs (tRNAs) are small molecules that have a central role in protein synthesis. Other RNA molecules, called ribozymes, function as enzymes to catalyze chemical transformations. Although ribozymes most often catalyze cleavage of the... 

Deoxyribonucleic acid is the genetic material such that the information to make all the functional macromolecules of the cell is preserved in DNA (Sinden, 1994). Ribonucleic acids occur in three functionally different classes messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA) (Simons and Grun-berg-Manago, 1997). Messenger RNA serves to carry the information encoded from DNA to the sites of protein synthesis in the cell where this information is translated into a polypeptide sequence. Ribosomal RNA is the component of ribosome which serves as the site of protein synthesis. Transfer RNA (tRNA) serves as a carrier of amino acid residues for protein synthesis. Amino acids are attached as aminoacyl esters to the 3 -termini of the tRNA to form aminoacyl-tRNA, which is the substrate for protein biosynthesis. 

Genes specify the kinds of proteins that are made by cells, but DNA is not the direct template for protein synthesis. Rather, the templates for protein synthesis are RNA (ribonucleic acid) molecules. In particular, a class of RNA molecules called messenger RNA (mRNA) are the information-carrying intermediates in protein synthesis. Other RNA... 

Messenger RNA transfers genetic information from DNA to ribosomes for protein synthesis. Transfer RNA and ribosomal RNA are also involved in protein synthesis. RNA can be structurally complex single RNA strands can be folded into hairpins, double-stranded regions, or complex loops. 

Three types of RNA are fonnd in cells. Transfer RNA (tRNA) carries amino acids to the site of protein synthesis. Ribosomal RNA (rRNA) along with protein makes np ribosomes (the mechanism that synthesizes protein). Messenger RNA (mRNA) is the code or template for protein synthesis. Special enzymes synthesize the different forms of RNA. 

Three forms of ribonucleic acid are found in cells messenger RNA, ribosomal RNA, and transfer RNA. Each form serves an important function during protein synthesis. All RNA molecules are single stranded, but some contain loops or folds. 

In bacterial cells, nucleic acids are found in the form of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA carries the genetic blueprint for the cell and RNA acts as an intermediary molecule to convert the blueprint into proteins [8]. RNA has three forms namely, ribosomal, messenger and transfer RNAs. All the three types of RNA are essential for protein synthesis. Ribosomal RNA is the most abundant macromolecule, next to proteins, in an actively growing prokaryotic cell. It is a major component of the ribosome, the cellular machinery used to synthesize new proteins. There are three ribosomal RNA molecules in prokaryotes namely 5S (ca. 120 nucleotides), 16S (1500 nucleotides), and 23S (2900 nucleotides). 

Because of space limitation this review will mostly cover RNA synthesis and maturation of protein-encoding messenger RNAs (mRNAs). However, similar mechanisms are used to regulate synthesis of other types of RNA molecules. 

On the basis of the early observation that the increases in microsomal enzyme activity produced by phenobarbital and 3-methylcholanthrene were blocked by actinomycin-D, it was suggested that enzyme induction resulted from the synthesis of new enzyme protein which was, in turn, dependent upon the DNA-directed synthesis of a messenger-like RNA. Treatment of rats with 3-methylcholanthrene causes an increase of about 40% in the level of RNA in rat liver nuclei and the nuclear RNA from 3-methylcholanthrene-treated rats is more active in directing protein synthesis than RNA from control animals. Moreover, the in vitro incorporation of radioactive precursors such as orotic acid or cytidine triphosphate into nuclear RNA is 50 to 100% greater in preparations from 3-methylcholanthrene-treated animals than controls. It is of interest that treatment of rats with phenobarbital has been recently reported to result in a marked suppression of endogenous hepatic ribonuclease activity. 

Cellular protein biosynthesis involves the following steps. One strand of double-stranded DNA serves as a template strand for the synthesis of a complementary single-stranded messenger ribonucleic acid (mRNA) in a process called transcription. This mRNA in turn serves as a template to direct the synthesis of the protein in a process called translation. The codons of the mRNA are read sequentially by transfer RNA (tRNA) molecules, which bind specifically to the mRNA via triplets of nucleotides that are complementary to the particular codon, called an anticodon. Protein synthesis occurs on a ribosome, a complex consisting of more than 50 different proteins and several stmctural RNA molecules, which moves along the mRNA and mediates the binding of the tRNA molecules and the formation of the nascent peptide chain. The tRNA molecule carries an activated form of the specific amino acid to the ribosome where it is added to the end of the growing peptide chain. There is at least one tRNA for each amino acid. 

Messenger RNA (mRNA) serves to carry the information or message that is encoded in genes to the sites of protein synthesis in the cell, where this information is translated into a polypeptide sequence. Because mRNA molecules are transcribed copies of the protein-coding genetic units that comprise most of DNA, mRNA is said to be the DNA-like RNA. ... 

Messenger RNA (mRNA) carries genetic messages from DNA to ribosomes, small granular particles in the cytoplasm of a cell where protein synthesis takes place. 

The infectious cycle of a (+)-strand RNA virus such as the hepatitis C virus differs by the fate of the viral RNA genome in the infected cell. Upon entry into the cell, the HCV genome is used as a messenger RNA to drive the synthesis of a large polyprotein precursor of about 3,000 residues [2]. The structural proteins are excised from the precursor by host cell signal peptidase. 

Those cytoplasmic RNA molecules that serve as templates for protein synthesis (ie, that transfer genetic information from DNA to the protein-synthesizing machinery) are designated messenger RNAs, or mRNAs. Many other cytoplasmic RNA molecules (ribosomal RNAs rRNAs) have strucmral roles wherein they con-... 

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