Biology 1002B Lecture Notes - Lecture 16: Permease, Plasmid, Repressor
1 Apr 2016
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Describe / draw the basic structure / function of the lac operon. In the metabolism of lactose, we have three genes which code for the metabolism. Lac z , lac y , lac a. These three genes are adjacent to one another in the order of zya. Codes for protein b - galactosidase, which converts lactose into glucose and galactose. When lactose is absent, the repressor binds to operator, blocking rna polymerase from binding to promoter. *if it makes rna, it"s rna polymerase; if it makes dna it"s dna polymerase. Not al(cid:449)a(cid:455)s (cid:271)ou(cid:374)d, so(cid:373)eti(cid:373)es (cid:272)o(cid:373)es off to allo(cid:449) a lo(cid:449) (cid:272)o(cid:374)(cid:272)e(cid:374)tratio(cid:374) of the ge(cid:374)e i(cid:374) (cid:272)ell . The low presence of beta-galactosidase converts it in to allolactose. Binds to repressor, which can no longer bind to operator. Rna polymerase can do its thang now (cid:894)o(cid:374)(cid:272)e repressor (cid:272)o(cid:373)es off ) In absence of lactose, lac repressor prevents transcription. Active lac repressor expressed from laci gene binds to operator.
