2E - Gene Regulation Flashcards
gene regulation
the control of
gene expression, typically achieved by switching transcription on or of
regulatory gene
segment of
DNA responsible for producing
proteins that control the
expression of other genes
(repressor or activator proteins)
structural gene
a segment
of DNA that codes for proteins that play a role in the structure or function of a cell or organism
(enzymes, transport proteins, receptors,
or peptide hormones.)
where are structural genes typically found
often found downstream (towards the 3’ end of the
coding strand) of the regulatory gene that controls them.
operon
a cluster of linked genes
that all share a common promoter and operator and are transcribed
at the same time
what allows operators to control gene expression
Because operators are always located downstream of the gene’s promoter region, they can be used as a binding site for repressor or activator proteins
- can control if RNA polymerase can move downstream from promoter region (aka if the gene can be transcribed)
trp operator
a series of genes
within certain species of bacteria that encode for the production of
the amino acid tryptophan
what is the primary function of trp operon
The trp operon regulates the production of enzymes required for the synthesis of tryptophan, ensuring tryptophan is only produced when levels are low.
how does repression in trp operon work
When tryptophan levels are high, tryptophan binds to the repressor protein, activating it. The active repressor binds to the operator, blocking RNA polymerase from transcribing the structural genes.
What is the role of the trp operon in E. coli?
It regulates the production of tryptophan by controlling the expression of genes involved in its biosynthesis, based on the cell’s tryptophan levels.
What is attenuation, and how does it regulate the trp operon?
attenuation halts transcription prematurely based on the availability of tRNA-bound tryptophan. If tRNA-bound tryptophan is sufficient, a terminator hairpin loop forms, stopping transcription. If not, an antiterminator loop forms, allowing transcription to continue.
