Biology 1202B Lecture Notes - Lecture 21: Rna World, Ribozyme, Xist (Gene)
6 Apr 2016
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Biology 1202b: lecture 21 rna world and rna. Rna world hypothesis: rna stored genetic information, rna catalyzed chemical reactions (ribozymes, served dna and protein like functions. Later in evolutionary time: dna took over as hereditary material, proteins became the major catalysts for reactions. Transition not entirely complete: rna still catalyzes several fundamental reactions. Life requires ability to catalyze reactions that lead, directly or indirectly to the production of more molecules like themselves. Rna has the unique potential to act as both information carrier and catalyst: assembly of rna polymers in the rna world is random. Single stranded rna can fold into many different structures. Generate large pool of random dna: transcribe. Rna molecules which have specific biochemical properties isolated: these properties include catalyzing a variety of reactions. Main difference between protein enzymes and ribozymes is reaction speed not diversity of reactions. Alternate conformations have different biochemical properties: e. g. ligase function or nuclease (dna cleavage)
