miRNAs are small single stranded RNA molecules composed of 22-23 nucleotides. These RNA negatively regulate gene expression by means of sequence-specific base pairing with target mRNAs. These molecules are encoded by genes that are transcribed from DNA, but are not translated into protein.
1. What are non-coding RNA? How are miRNA related to non-coding RNAs and what is the function of miRNA?
Non-coding RNA are involved in very diverse regulatory actions within cells. The relation between miRNA and non-coding RNA is that miRNA are a non-coding RNA class of genes that encode short length RNA molecules. Unlike RNA, miRNAs do not encode protein but rather inhibit the production of genes. At the post transctiptional level miRNA negatively regulate gene expression. The functions of mRNA are not limited to the regulation of developmentally timed events, but also diverse expression patterns and regulation of physiology.
2. Give a summary of the discovery, nature and function of miRNA.
While genetically screening for defects in the temporal control of post embryonic development in C. elegans researchers isolated a small temporal RNA (stRNA)which can be identified as lin-4. Lin-4
Some early observations determined that stRNA were unable to encode protein and that their actual function was unclear. Later these researchers determined that these small molecules were involved in the downregulation of mRNA during temporal regulation of development. The negative regulation of lin-4 protein expression requires the interaction of 3’-UTR of its mRNA and a functional lin-4 gene. After seven years, another stRNA was discovered called let-7 which was expressed in the fourth stage of larval C.elegans development.
3. What are the different types of RNAs in the cell and what are their functions?
siRNA- These molecules are involved in the mediation of RNA interference (RNA silencing). These molecules play a role in chromosome segregation,...