How do eukaryotic transcription factors exert their effects on transcription when their binding sites can be thousands of base pairs away from the promoter?
A. Regulatory proteins bind the sequences and then slide along the DNA until they reach an RNA polymerase bound to a promoter.
B. After binding to the site, the regulatory protein releases the DNA and is targeted to the polymerase via coactivator proteins.
C. Once bound to the site, the regulatory protein catalyzes the formation of an effector molecule that then travels to and binds the polymerase.
D. The DNA between the bound site and the polymerase-promoter complex loops out, increasing proximity.
D
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The presence of an antibiotic in the media where the bacteria are grown enables the selection of colonies grown from
(a) transformed cells. (b) nontransformed cells. (c) cells that have the gene for resistance to the antibiotic. (d) both a and c.
A strain of E. coli is trp? his? lac?. Which medium would this bacterium grow on?
A) minimal medium with lactose as the sugar, supplemented with histidine and tryptophan B) minimal medium with glucose as the sugar, supplemented with histidine and tryptophan C) minimal medium with glucose and lactose as the sugar D) minimal medium with glucose as the sugar
A randomly selected group of organisms from a family would show more genetic and anatomical
variability than a similar group randomly picked from a _____.
a. class b. genus c. order d. phylum e. kingdom
What mutations occurred in typical icefish that prevented production of hemoglobin?
A. fragmentation of both the alpha and beta genes B. deletion of the alpha gene and fragmentation of the beta gene C. deletion of both the alpha and beta genes D. fragmentation of the alpha gene and deletion of the beta gene E. destruction of red blood cells in the bone marrow