The order of events in a signaling pathway can be determined by the analysis of mutants. Cells that express a mutant defective Raf protein cannot be stimulated to proliferate uncontrollably by constitutively active RasD (dominant active). This indicates:

#Question id: 4063

#Unit 3. Fundamental Processes

Which statement correctly matches the three RNA polymerases with RNAs they synthesize?

#Question id: 4064

#Unit 3. Fundamental Processes

Which of the following mutations can result in a reduction of β-galactosidase?

#Question id: 4065

#Unit 3. Fundamental Processes

The NtrC protein from E. coli

a. is a σ54 RNA polymerase.  b. stimulates transcription of the glnA gene.

c. is activated by a protein kinase called NtrB.

d. binds both to an enhancer site upstream of the glnA gene and to RNA polymerase.

e. has ATPase activity.

#Question id: 4066

#Unit 3. Fundamental Processes

Specific DNA control elements in promoters can

a. interact with general transcription factors.

b. interact with repressor proteins. 

c. interact with activator proteins.

d. remain unavailable because of condensed chromatin.

#Question id: 4067

#Unit 3. Fundamental Processes

Reporter genes are used to

a. express enzymes that are not easily assayed in cell extracts.

b. express enzymes that are easily assayed in cell extracts.

c. characterize DNA control elements. 

d. characterize reporter plasmids.

#Question id: 4068

#Unit 3. Fundamental Processes

The three eukaryotic RNA polymerases can be distinguished by

a. the types of genes they transcribe.

b. the number and types of large subunits.

c. their differential sensitivities to cycloheximide.

d. their differential sensitivities to α-amanitin.