<prompt> which nNA contalne abnormal purine and pyrimidine:tRNA23SrRNA16SrRNA5SrRNA  <response>: Answer: a. tRNAtRNA molecule contain a high percentage of unusal bases, for example, dihydrouracil and have extensive intra-chain base pairing that leads to characteristic secondary and teiary structure- Lippincott 6th 418.The tRNA molecules contain a high percentage of unusual bases for example, dihydrouracil and have extensive intrachain base-pairing that leads to characteristic secondary and teiary structure.Transfer RNA is unique among nucleic acids in its content of unusual bases. An unusual base is any purine or pyrimidine ring except the usual A, G, C, and U from which all RNAs are 