DNA replication is studied in a newly discovered bacterium. It takes 30 min for the bacterium to complete a round of replication at 37oC. A Meselson-Stahl-type experiment was performed. The bacteria were grown for several generations in 14N-medium and then switched to 15N-medium. The DNA molecules were then analyzed.

If the mechanism of DNA replication in this bacterium were dispersive, what results would be found when the double-stranded DNA was analyzed in a CsCl gradient after two generations in 15N-medium?

#Question id: 4485

#Unit 3. Fundamental Processes

In multicellular organisms, regulatory sequences can spread thousands of nucleotides from the promoter—both upstream and downstream—and can be made up of tens of regulator binding sites. Often, these binding sites are grouped in units called_?

#Question id: 4486

#Unit 3. Fundamental Processes

Activators can recruit factors needed for polymerase to initiate or elongate transcription. In all of these functions, the activator is merely recruiting proteins to the promoter. In bacteria, RNA polymerase is the only protein that needs to be recruited; this is not the case in eukaryotes. Indeed, in eukaryotes, a given activator might work in all three ways:

#Question id: 4487

#Unit 3. Fundamental Processes

Choose correct statements about nucleosome modifiers

#Question id: 4488

#Unit 3. Fundamental Processes

One component of thecomplex bears bromodomains and thus binds to acetylated nucleosomes better than to unacetylated nucleosomes. Thus, a gene bearing acetylated nucleosomes at its promoter will likely have a higher affinity for the transcriptional machinery than one with unacetylated nucleosomes.

#Question id: 4489

#Unit 3. Fundamental Processes

HSP70 gene from Drosophila. This gene, activated by heat shock, is controlled by two activators GAGA binding factor and HSF,In response to heat shock, HSF binds to specific sites at the promoter and recruits a kinase, P-TEFb (positive transcription elongation factor). What is the proper mechanism of pausing and release of Pol II ?

#Question id: 4490

#Unit 3. Fundamental Processes

The human immunodeficiency virus (HIV), which causes AIDS, transcribes its genes from a promoter controlled by P-TEFb (and SEC). Again, polymerase initiates transcription at that promoter, under the control of which activator?