Regulation of Gene Expression Flashcards
What is spatial restriction of gene expression?
Differences in regulation of gene expression in different organs, tissues, cell types, or cells.
What is temporal restriction of gene expression?
Differences in regulation of gene expression during different points of development, differentiation, cell cycle or inducible expression.
Through what molecules does regulation of gene expression occur?
Specific transcription factors
What is an operon?
A series sequentially grouped genes that encode proteins whose functions are involved in similar biological pathways
Which of the following are true of operons? All of the genes are controlled by the same cis-acting elements; all of the genes are expressed as polycistronic mRNA; All of the genes can be turned on or off at the same time
All are true
What is the segment if DNA that regulates the expression of genes present in an operon?
Operators
Do transcription factors bound to operators typicaly activate or repress gene expression?
Repress
What is the lac operon?
Prokaryotic operon that contains lacZ, lacY, and lacA all of which encode proteins that metabolize lactose
Under what cellular conditions is the lac operon mostly highly expressed?
When glucose is absent or very low and when lactose is available
What elements are contained in the lac operon?
The lac promoter, operator, CAP binding site, and three genes
What is encoded by the lacI gene?
The lac repressor
What is CAP? What is its function with regards to the lac operon? What is it activated by?
Catabolite Activator Protein is activated by cAMP and binds to the CAP-binding site of the lac operon to activate it
What is the activity of lac operon expression when glucose is the only available sugar?
None of the lac operon genes are transcribed
What is the mechanism of catabolite repression with regards to the lac operon?
The presence of glucose inhibits the activity of adenylyl cyclase- which causes low levels of cAMP and low ability of CAP to bind and activate transcription
What is the level of lac operon transcription when both lactose and glucose are present?
Transcription of the operon is present but low
What is the Trp Operon?
A series of 5 prokaryotic genes important for the synthesis of Tryptophan
What is the effect of the binding of Trp to the Trp operon repressor?
It enhances the binding of the repressor to the operator
What is attenuation?
The attenuating or pausing of RNA Pol once transcription has been initiated
What is the stringent response?
Gene expression regulation in response to amino acid starvation
The formation of which molecule is catalyzed by RelA?
Guanosine 5’-disphosphate 3’-diphosphate (ppGpp)
Operons expressing what kind of proteins are suceptible to negative feedback inhibition?
Ribosomal proteins
What area of specific transcription factors allows the binding of additional proteins or to facilitate the recruitment of the transcriptional initiation complex to inititate transcription
Transcriptional activation domain
What is combinatorial control?
A eukaryotic method of gene expression regulation by which a limited set of regulatory proteins exert specific effects on gene transcription via unique combinations and interactions
Through wat mechanism does cortisol affect gene expression?
Cortisol binds to its intracellular receptor, which moves into the nucleus, dimerizes and binds to the glucocorticoid response element in DNA
