Gene Regulation Flashcards
Do prokaryotic genomes contain introns?
No
Can transcription and translation occur simultaneously in prokaryotes?
Yes.
What mechanism allows prokaryotes to translate multiple genes from the same mRNA transcript?
Operons: clusters of genes under the control of a single promoter.
What is the lac operon?
A collection of genes that regulate the metabolism of lactose in E. coli.
What is the role of lacI?
lacI is a repressor gene that regulates binding of RNA polymerase to lacO (the operator).
How does the addition of lactose result in the subsequent metabolism of lactose?
A small amount of added lactose becomes transformed into allolactose, which is an inducer that prevents the binding of the repressor to lacO.
What is polycistronic mRNA?
mRNA that encodes multiple genes.
What is bacterial conjugation?
A mechanism of horizontal gene transfer in bacteria.
What are cis-acting elements?
Elements encoded on the same chromosome as the gene they regulate (promoters, enhancers)
What are trans-acting factors?
Factors that may be encoded on different chromosomes from the genes they influence (transcription factors, polymerases)
What is the lacI s mutation? (superrepressor)
A mutation of the repressor that cannot bind the inducer, thus lacZ (which produces b-galactosidase) is always repressed.
What is the dominance relationship between lacI alleles?
lacI s > lacI + > lacI -
What does it mean if a gene is constitutive?
The gene is always expressed.
What does it mean if a gene is inducible?
The gene can either be expressed or repressed.
Do nucleosomes inhibit transcription?
Yes, it is more difficult for polymerases to bind promoters when genetic information is tightly wrapped in nucleosomes.
