Lecture 10
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some genes or activities are constitutive meaning always ____
Expressed or on
mRNA half-life is short which can allow
Quick response
Strong promoters
Feature high rates of transcription
Weak promoters
Feture low rates of transcription
Shine-Dalgarno sequences can bind the ____ rRNA and hence the ribosome well or poorly, thus affecting ____
16S/ Translation
Sigma factors recognizes __ and __consensus sites
-10/-35
Different genes have differnt ____ sites, allowing ____ ____ by alternative sigma factors
consensus/ coordinated regulation
Negative regulation by repression DNA binding by a _______to an operator upstream of regulated gene(s)
repressor protein
Repressor binds to DNA
No transcription
Repressor doesn’t bind DNA
Transcription
What binds to a repressor and prevents DNA binding
Inducer
What binds to a repressor and allows DNA binding
Corepressor
Arginine biosynthesis pathway cellwill only make arginine if it…..
If it is not present in the medium
Genes for lactose transport and degredation are only made when lactose is present
Catabolism of lactose
REpressor bound to inducer lactose
Transcription proceeds
Repressor alone: binds operator DNA, blocks RNAP
No transcription
Binding of an ____ to DNA at activator binding sites ____ transcription
Activator protein/ Induces
Mal promoter is ____ poor match to concensus sequence
Weak
Maltose acts as an ____allowing binding of the activator
Transcription proceeds
Activator bind can increase transcrition by
Helping RNAP recognoze promoter Binding RNAP and promoter directly “tethering” it to the promoter
Activator binding results in a change in the structure of the DNA
Bending
External signal is detected by a sensor that transmits it to the rest of the regulatory machinery
Signal transduction
Two component regulatory system
Sensor kinase (transmembrane) Response regulator (cytoplasm)
Enzyme that phosphorylates compounds using y-phosphate from ATP
Kinase