LIFESCI 7A Lecture 9: Week 7 Notes- Transcriptional Regulation in Prokaryotes
Document Summary
Intro: gene regulation in prokaryotes is simpler bc dna isn"t packaged in nucleosomes, mrna isn"t processed, transcription/translation aren"t separated by nuclear envelope. Expressing protein-coding gene includes transcription of gene into mrna and translation of mrna into protein. Positive regulation: a regulatory molecule (usually protein) binds to the dna at a site near the gene for transcription to take place. Negative regulation: a regulatory molecules binds to dna near the gene for transcription to be prevented: most promoters have sequences that recruit proteins needed for transcription when transcription of gene is activated. Most promoters in eukaryotes have 5"-tataaa-3" 25-35 base pairs upstream from transcription start site. Binding sites for activators or repressors can be found upstream, downstream, or overlapping with the promoter. If activator isn"t present or isn"t able to bind with dna, rna polymerase isn"t recruited to the promoter--> transcription doesn"t occur.
