control of gene expression Flashcards
what is a transcription factor?
proteins that affect the rate of transcription
what does post-translational control involve?
modifications to proteins that have been synthesized e.g…
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what does the regulatory gene code for?
regulatory protein
what do the structural genes do in lac operon?
code for enzyme lactase
what does the repressor protein do?
prevents transcription of structural genes if lactose is not present by preventing RNA polymerase binding to DNA (the promoter) triggering transcription
what is an operon?
a group of genes under the control of the same regulatory mechanism
what is the advantage of an operon?
save resources,, if certain gene products are not needed then the genes for the production of the product are switched off`
what happens in the lac operon if lactose is present?
lactose binds to repressor protein causing change in shape so it cant bind to the operator
results in RNA polymerase being able to bind to the promoter, three structural genes transcribed and enzymes are synthesized
what is the section of DNA that is the binding site for RNA polymerase called?
the promoter
what is produced after transcription?
pre-mRNA
what is the non-coding part of DNA called?
introns
what is the coding part of DNA called?
exons
