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Chapter 8 Practice Questions.
Which of the following statements is NOT true about the differences between liver cells and kidney cells in the same organism?
(A) They contain the same genes, but express them differently.
(B) They contain different genes.
(C) They contain different sets of proteins.
The cell can change the expression of it genes in response to external signals. (T or F?)
Although all of the step involved in expressing a gene can in principle be regulated, for most genes the most important point of control is?
A gene regulatory protein usually binds to which groove in the DNA double helix?
When a gene regulatory protein binds to DNA, its most important interactions occur with which parts of the DNA?
Which of the following is the initiation site in a gene?
The part of a promoter where transcription actually begins.
In bacteria, when transcription regulators bind to regulatory DNA sequences close to where RNA polymerase binds, they...
Activate or repress transcription of the gene depending upon where they are located relative to the promoter.
What is the definition of an operon?
A set of genes (found in bacteria not eukaryotes) that is transcribed into a single mRNA.
Accurately describe the expression of the repressor protein of the tryptophan operon?
The gene for the tryptophan repressor is expressed constitutively.
In a bacterial cell, the tryptophan operon encodes the genes needed to synthesize tryptophan when the concentration of tryptophan inside the cell is high...?
It activates typtophan repressor which shuts down the tryptophan operon.
Which of the following describes the lac operon in E. coli when both lactose and glucose are present in the culture medium?
Neither CAP not the lac repressor is bound to the lac operon's regulatory DNA, and the lac operon is not expressed.
In eukaryotes, where do trascription regulators bind?
Either upstream or downstream from a gene.
Which of the following is false?
eukaryotic gene activator proteins stimulate trasncription initiation by recruiting a DNA polymerase to the promoter.
a single transcription regulator, if expressed in the appropriate precursor cell, can trigger the formation of a specialized cell type of even an entire organ.