Three major forms of RNA exist in any living cell…
1. mRNA: The process of transcription results the synthesis of mRNA from DNA. These mRNAs carries genetic information of DNA from nucleus to cytoplasm (ribosome), the sites of protein synthesis. It can be monocistronic as in eukaryotes or polycistronic in prokaryotes.
2. tRNA: At the time of protein synthesis these RNAs recognises the coded genetic information of mRNA and brings specific amino acids at the site of growing poly peptide chain. There is at least one tRNA for each amino acid.
3. rRNA: It is synthesised in nucleolus. In cytoplasm ribosomal RNA and protein combine together to form a nucleoprotein called a ribosome.
These are the most abundant form of RNA and counts about 80% of total cellular RNA.
Some Other functions of nucleotides….
1. Nucleoside triphosphate (especially ATP) provides chemical energy to drive a wide variety of cellular reactions.
2. They serve as precursor for nucleic acid synthesis (phosphodiester linkage, phosphoanhydride linkage).
3. Adenine nucleotides are components of major enzyme cofactors.
4. Some nucleotides are regulatory molecules like cyclic AMP.
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