MIC 205 Lecture Notes - Lecture 13: Operon, Repressor, Tryptophan
Document Summary
Mic 205 - microbiology - microbial genetics lecture 03. Polyribosome - multiple ribosomes translating one mrna. Of genes are expressed at all times: housekeeping genes. To stop synthesis of a certain protein, cell shuts down the transcription of the corresponding gene: when necessary, a cell can stop translation, this mechanism can be accomplished at the gene level. Majority of genes are controlled under transcription - 75% of genes are transcribed and translated: those genes are needed all the time (housekeeping) Regulatory genes are transcribed and translated into repressors specific to the cell. Genes that have similar functions are grouped together into operons: promoter genes terminator, polycistronic mrna carries the information of multiple genes. Inducible operons must be activated by inducers: regulatory genes are transcribed and translated into inducers specific to the cell, inducers bind to the operator and act as a key. Inducible lactose (lac) operon - occurs/activated in absence of lactose.
