BIOL 0280 Lecture Notes - Lecture 19: Exonuclease, Base Pair, Transcription Bubble
7 Nov 2016
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Document Summary
All rna molecules (except some viruses) derived from information permanently stored in dna. During replication, the entire genome is usually copied. During transcription, only particular genes/groups of genes are transcribed at any one time (some portions of dna genome are never transcribed) Only one dna strand serves as a template for transcription. Rnaps don"t require a primer, don"t have 3"-->5" exonuclease activity (no proofreading = less accurate, but much shorter and mutations are not super high stakes) Synthesized de novo - no primer is required. Active site of rnap has same chemistry as dnap. Mg2+ ions coordinated by asp, help coordinate the triphosphate tail. 3"-->5" dna template strand = complementary to rna transcript. 5"-->3" rna transcript = same as dna coding strand. Rna polymerases recognize and bind to promoters: specific dna sequences. 10, -35 regions in e. coli are promoter sequences. Sigma factors recognize promoter and helps rnap to forms complex at promoter sequence.
