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Gene Expression: 1.1 Proteins interacting with DNA turn Procaryotic genes ON or OFF in response to environmental changes

Terms in this set (10)

Gene regulation
turning on and off of genes
Gene expression
overall process of information flow from genes to proteins
The control of gene expression allows cells to...
Produce specific kinds of proteins when and where they are needed
Operon
- control sequences + a cluster of genes with related functions.

- only exist in prokaryotes (bacteria)
When E.coli encounters lactose...
All the enzymes needed for its metabolism are made at once by using the lactose operon
The lactose operon includes...
- three adjacent utilization genes

- a promoter sequence

- an operator sequence
Promoter sequence
where RNA polymerase binds and initiates transcription of all three lactose genes
Operator sequence
Where a repressor can bind and block RNA polymerase action
Regulation of lac operon
- A regulatory gene located outside the operon codes for a repressor protein

- in the absence of lactose, the repressor binds to the operator and prevents RNA polymerase action

-Lactose inativas the repressor, so the operator is unblocked

- RNA polymerase can bind to promoter

- All three genes of the operon are transcribed
Two types of repressor controlled operons
- lac operon: repressor is active when alone and inactive when bound to lactose

-Trp bacterial operon: the repressor is inactive when alone and active when bound to the amino act tryptophan (trp)
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