BIOL 14a Lecture Notes - Lecture 36: Body Plan, Embryonic Stem Cell, Somatic Cell Nuclear Transfer
12 Dec 2016
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Document Summary
Dna elements (cic-acting) and transcription factor proteins (trans-acting) Promoter strength: affinity of promoter for rna pol and/or transcription factors. Natural promoters vary widely in promoter strength. Promoter strength depends on promoter"s dna sequence. Mutations that increase deviation, weakens promoter"s physical interactions with transcriptional proteins. Mutations that make the promoter sequence more similar to the consensus sequence strengthen promoter"s physical interactions with transcriptional proteins. Prokaryotic gene transcription can be co-regulated in an operon. Lac operon is off unless lactoseis present. Lac operon = 3 genes to break down the disaccharide lactose. The regulatory gene codes for an active form of the lac repressor. An isomer of lactose acts as an inducer. Both trp and lac operons involve the negative control of genes because operons are turned off by active forms of repressor proteins. Regulatory proteins activate (activators) or repres (repressors) transcription. Cis - close by, on the same gene, the part directly affects the gene.
