tRNA combines with
i.e. (mRNA): (308-310-Harper 28th) (554-U-satyanarayan 3rd) (418-Lippincot's 5th)Transfer RNA (tRNA)* tRNA are the smallest (4S) of the three major types of RNA molecules (15%)* The tRNA molecules contain a high percentage of unusual bases (for example-dihydrouracil) and have extensive inter chain base pairing that leads to characteristic secondary and tertiary structures* Each tRNA serves as an "adaptor " molecules that carries its specific amino acid - Covalently attached to its 3 ' end to site ofprotein synthesis. There it recognizes the genetic code sequence of an mRNA, which specifies the addition of its aminoacid to the growing peptide chain. mRNAs and si RNAs cause inhibition of gene expression by decreasing specific protein production, albeit via distinct mechanisms, Both represent exciting new potential targets for therapeutic drug development1. miRNAs - Micro RNAs are typically 21-25 nucleotides long RNA species derived from RNA polymerase II*** transcription units. The small processed mature miRNAs typically hybridize via the formation of imperfect RNA-RNA duplexes within the 3'-untransIated regions of specific target mRNAs leading via poorly understood mechanism to translation arrest2. SiRNAs - silencing RNAs 21 = 25nt in length generated by selective nucleolytic degradation of double stranded RNAs of cellular or viral origin* These short siRNAs usually form perfect RNA-RNA hybrids* SiRNAs are frequently used to decrease or "Knock down99 specific protein levels
DNA
mRNA
miRNA
siRNA
Molecular Genetics