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# RNA ## Types of RNA Molecules 1. Messenger RNAs (mRNAs) - intermediates that carry genetic information from DNA to the ribosomes 2. Transfer RNAs (tRNAs) - adaptors between amino acids and the codons in mRNA 3. Ribosomal RNAs (rRNAs) - structural and catalytic components of ribosomes 4. Small inte...

# RNA ## Types of RNA Molecules 1. Messenger RNAs (mRNAs) - intermediates that carry genetic information from DNA to the ribosomes 2. Transfer RNAs (tRNAs) - adaptors between amino acids and the codons in mRNA 3. Ribosomal RNAs (rRNAs) - structural and catalytic components of ribosomes 4. Small interfering RNAs (siRNA) - RNA interference (RNAi) 5. Long non-coding RNAs (long ncRNAs) - transcription 6. MicroRNAs (miRNAs) - RNA interference (RNAi) 7. Ribozymes - RNA enzymes ## Messenger RNA (mRNA) Carries the instructions for building a protein ## RNA Structure - Intrinsically single stranded - Unable to form B-form helix due to bulky 2'-OH - When helical, RNA adopts A-form geometry - Deep & narrow major groove; wide minor groove - Secondary structure observed in rRNA and tRNA, & assumed to be in mRNA - The 3' end is polyadenylated ### PolyA tail is NOT coding - It is added after transcription - Stabilises mRNA - Removal of polyA degrades RNA - Also inhibits translation ## Ribosomal RNA (rRNA) - Complex - Makes up the ribosomes - Ribosomes are the "protein factories" - Large macromolecular assemblies - Composed of many proteins rRNA molecules ## Transfer RNA (tRNA) - Intermediary between the nucleic acid & protein worlds - Acts as a translator