Types of RNA

Posted by bhavin | Posted in , , , , | Posted on 11:18 AM

RNA
RNA stands for ribonucleic acid. It is a nucleic acid that comprises of a big chain of the nucleotide units. Each nucleotide has a ribose sugar, a phosphate and a nitrogenous base. Ribonucleic acid (RNA) is similar to the deoxyribonucleic acid (DNA) to a great extent. The only difference lies in some of the structural details. DNA is double stranded and RNA is single stranded; DNA nucleotides contain deoxyribose and RNA contains only ribose; DNA has the base thymine instead of uracil as present in RNA.

There are generally three types of RNA. These three types include Messenger RNA (mRNA), Ribosomal RNA (rRNA) and Transfer RNA (tRNA). Now let us have a brief overview on each of these types of RNA.

Messenger RNA- mRNA is the replica of the data that is being transmitted on DNA by the genes. The function of this mRNA is to carry the data that is present in the DNA to the translation mechanisms. The mRNA is usually synthesized from the DNA’s gene segment. This RNA has all the data of the amino acids in proteins that are to be synthesized on the primary sequence. It transmits the code in the cytoplasm where the synthesis of proteins takes place. The messenger RNA is heterogeneous in sequence as well as structure. Due to this diversity in size and sequence, there is not a specific structure of mRNA determined. It always has a five-inch cap containing the triphosphate linkages. This cap is an identification that the RNA molecule present in the structure is the mRNA.

Ribosomal RNA- the rRNA is a constituent of ribosome’s that are the regarded as the protein synthesis factories in the cells. The rRNA molecules are found profusely in the cell. 80% of the RNA molecules found in the cells are comprised of the rRNA. The rRNA plays different roles in the process of protein synthesis. Firstly, it plays a catalytic role by forming a part of peptidyl transferrase activity. Then, it plays the recognition role by getting occupied in the exact positioning of the tRNA and the mRNA. And finally, it plays the structural role by getting folded into 3-D shapes and forming a gibbet, wherein the assembly of the ribosomal protein takes place.

Transfer RNA- the tRNA is referred as the data adapter molecule. It bridges the gap directly between the DNA information and the sequence of amino acids in proteins. Thus, it can interpret the information contained in the DNA. There are more than twenty various types of tRNA molecules present in the cells all between the range of 75 - 95 NT. The tRNA’s in all the organisms features a similar structure and orientation. It has three loops and four arms and sometimes, it has an extra loop. The synthesis of the tRNA takes place in two parts. The tRNA body is copied from the tRNA gene. All the tRNA molecules share the same type of acceptor stems and this is added after the synthesis of the body. This is generally replaced at the lifetime of the tRNA molecule.

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