EEMB 129 Lecture Notes - Lecture 20: Trp Operon, Catabolite Repression, Arabinose

• School: UCSB
• Department: Ecology, Evolution & Marine Biology
• Course: EEMB 129
• Professor: Scott Hodges

Document Summary

1:02 pm repressors of lac protein can act as tetramer of lac protein. Can bind to o1 and o2 or o3(o2 and o3 on the same side) Mutation to either o2 or o3 would not affect much. Complication 2- repressor and activator arcc of arabinose operon. Turn genes on when sugar is avilable arac- mutant can act as activator and repressor. Bind arabinose and assist binding of rna polymerase. When there is no arabinose, form a loop. Create physical contact between activator and rna polymerase. A molecular mechanism exists to fine tune transcription. Even without repressor protein, mutants still reduce expression of trp expression. Initiation at trp operon can produce 2 different transcripts. Sometimes only part of the operon is transcribe-> so no protein. Short vs. long transcription mediated by mrna structure. When try is present-> rna polymerase reading template strain-> When try is absent-> ribosomes has little charged trna and.