What is RNA?
RNA is short for ribonucleic acid. RNA biology is one of the three major biological macromolecules, along with DNA and proteins. These macromolecules are essential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides. But unlike DNA, RNA is found in nature as a single strand folded onto itself, rather than a paired double strand.
The role of RNA
Since protein encoding genomic DNA cannot leave the nucleus, it needs a messenger to enable protein synthesis on other locations in the cell. And that’s where RNA comes in. RNA is a mobile copy of DNA which can function as a building plan for protein synthesis. To create the RNA copy of the DNA, first the double helix structure of DNA is unzipped to expose the individual strands to several enzymes, including helicase and topoisomerase, unwinding DNA. Subsequently, Reverse-transcriptase enzymes make a complimentary copy of a gene encoded in the DNA. This copy is called the messenger RNA (mRNA) of this gene. This mRNA molecule carries the building plan for the construction of the encoded protein. The process of translating DNA into mRNA is known as transcription.
The mRNA is then transported outside of the nucleus, to the molecular machine responsible for manufacturing proteins, the ribosome. The ribosome translates the mRNA into amino acids to create a polypeptide chain that will become a protein. The ribosome forms a protein in three steps:
- Initiation: The specific amino acid is brought to the Ribosome by transfer RNA (tRNA)
- Elongation: Each amino acid is sequentially connected by peptide bonds, forming a polypeptide chain.
- Termination: the completed polypeptide chain is released from the ribosome and is folded into its final protein state.
Proteins are required for the structure, function, and regulation of the body’s tissues and organs; their functionality is seemingly endless.
What is miRNA and why is it important?
miRNA stands for microRNA. MicroRNA contains 18 to 28 nucleotides and are small non-coding molecules. This means that they do not serve as a transporter of protein composition information, but have a function on their own. They play an important role in the posttranscriptional regulation of protein expression. A miRNA molecule pairs with a complementary sequence within mRNA molecules. As a result, these mRNA molecules are silenced. One miRNA is able to target multiple genes thus regulating the expression of several proteins. Many of the miRNAs are evolutionary conserved, which implies they have biological functions that are of vital importance. Many scientist believe that these miRNAs have played a crucial role in the evolution to complex organisms.