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What determines the nucleotide sequence of an RNA strand?
Complementary base pairing with the DNA template during transcription
What energy drives the transcription reaction forward?
The hydrolysis of high-energy bonds of ribonucleoside triphosphates during elongation
How does the error rate of RNA polymerase compare to the error rate of DNA polymerase (1 error in 10^7 nucleotides)?
To begin transcription, RNA polymerase recognizes nucleotide sequences in what region of DNA?
What is the name of the subunit of bacterial RNA polymerase that recognizes the promoter of a gene?
In eucaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?
General transcription factors
The assembly of general transcription factors to a eucaryotic promoter begins at what site in a promoter?
The TATA box
How are bacterial mRNA transcription and translation separated spatially temporally?
Bacterial mRNAs are transcribed and translated simultaneously.
How are eucaryotic mRNA transcription and translation separated spatially and temporally?
Eucaryotic mRNAs are translated after they are exported from the nucleus.
True or False: Unlike the coding sequence of an exon, most of the nucleotide sequence of an intron is unimportant.
What structure is responsible for selecting and transporting only properly processed eucaryotic mRNAs into the cytoplasm?
The nuclear pore complex
Within the ribosome, the formation of peptide bonds is catalyzed by:
An RNA molecule in the large ribosomal subunit.
At what site do all charged tRNAs (with the exception of the initiator tRNA) first bind on the ribosome?
What is a polyribosome?
A cluster of ribosomes translating the same mRNA, but positioned at different sites along the mRNA
Proteasomes act primarily on proteins that have been marked for destruction by the covalent attachment of which small protein?
Which sugar cannot be readily made from formaldehyde in experiments simulating conditions on primitive Earth?
A typical differentiated human cell will express how many of its approximately 25,000 genes?
From 5,000 to 15,000 genes.
True or False: Different cell types that respond to the same hormone usually turn on the same sets of genes.
Although all of the steps involved in expressing a gene can in principle be regulated, for most genes the most important point of control is:
When a gene regulatory protein binds to DNA, its most important interactions occur with which parts of the DNA?
True or False: When a gene regulatory protein binds to DNA, it typically disrupts the hydrogen bonding between base pairs.
In bacteria, when transcription regulators bind to regulatory DNA sequences close to where RNA polymerase binds, they do what?
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 but not eucaryotes) that is transcribed into a single mRNA
What is the expression of the repressor protein of the tryptophan operon?
The gene for the tryptophan repressor is expressed constitutively.
In the bacterial cell, the tryptophan operon encodes the genes needed to synthesize tryptophan. When the concentration of tryptophan inside the cell is high what happens to tryptophan repressor?
It activates tryptophan repressor which shuts down the tryptophan operon.
Describe the lac operon in E. coli when lactose, but not glucose, is present in the culture medium.
CAP, but not the lac repressor, is bound to the lac operon's regulatory DNA, and the lac operon is expressed.
Describe the lac operon in E. coli when both lactose and glucose are present in the culture medium.
Neither CAP nor the lac repressor is bound to the lac operon's regulatory DNA, and the lac operon is not expressed.
True or False: Eucaryotic gene activator proteins stimulate transcription initiation by recruiting a DNA polymerase to the promoter.
True or False: The general transcription factors that assemble at a eucaryotic promoter are different, depending on the specific gene being transcribed by polymerase II.
True or False: Even though control of eucaryotic gene expression is combinatorial, the effect of a single gene regulatory protein can still be decisive in switching any particular gene on or off.
True or False: Differentiated cells in multicellular organisms require hormonal input to 'remember' what type of cell they should be.
True or False: A single transcription regulator, if expressed in the appropriate precursor cell, can trigger the formation of a specialized cell type or even an entire organ.
What is an example of epigenetic inheritance?
The inheritance of methylation patters in DNA, the inheritance of patterns of chromosome condensation, or the inheritance of a regulatory protein that activates its own transcription.
What factors are involved in post-transcriptional control?
Riboswitches, microRNA, and RNA interference
In bacteria, if a protein binds to the ribosomal binding site on an mRNA, what is the consequence?
The small ribosomal subunit will not be able to bind to the mRNA, and translation will be inhibited.
What is the ultimate fate of an mRNA that is targeted by a microRNA (miRNA) based on their complementary nucleotide sequences?
The mRNA will be destroyed by a nuclease.
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