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What is the role of the promoter region in the regulation of gene expression?
The promoter region is the site of a gene where RNA polymerase and other transcription factors bind to DNA, upstream from the gene locus. A mutation in this region commonly results in a decrease in the amount of gene transcribed.
An enhancer region is a stretch of DNA that alters gene expression by binding transcription factors, while a silencer region is a site on the gene where repressor proteins bind. Introns are intervening non-coding segments of DNA that are not expressed in the final protein. Alternative splicing patterns of introns and exons allows for multiple proteins to be generated from a single gene.
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Which of the following are methods for termination of transcription in prokaryotes?
I. Release factor binding
II. Rho-mediated termination
III. Hairpin loop (stem loop) formation
The binding of release factors is a common way to terminate translation, not transcription.
Rho-mediated termination and hairpin loop formation are both common ways to terminate prokaryotic transcription. The formation of the hairpin loop disrupts the transcription machinery and the DNA-RNA interactions, which allows termination of transcription. Rho is a protein that is capable of binding single-stranded RNA and terminating transcription.
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What event is indicative of transcription initiation?
During the initiation of transcription, RNA polymerase and a group of transcription factors bind to the promoter for a given gene. This DNA segment signals the RNA polymerase where to begin creating the RNA strand.
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Which of the following best describes distant regulatory sequences that influence gene expression?
The correct answer is enhancer. Transcription factors and mediators bind enhancer regions of DNA and influence the transcription of distant genes by chromatin looping to the proximal promoter. Promoters are regulatory sequences, however, they are typically 2 kilobase pairs upstream of the gene for which they influence transcription. Introns and exons make up a gene and are the non-coding and coding regions of the gene, respectively. The transcriptional start site consists of the first few nucleotides that are transcribed into an mRNA sequence from a gene, usually containing the 5' untranslated region (UTR).
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When does alternative splicing occur?
The correct answer is following pre-mRNA transcription in the nucleus. Pre-mRNA contains introns and exons. Following transcription, splicing and alternative splicing occurs to remove introns and select exons, respectively, by the spliceosome. Following splicing, 3' poly adenylation and 5' capping occur to generate a mature mRNA transcript that will translocate to the cytosol and be translated by ribosomes.
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What element(s) do all eukaryotic promoter regions share?
Eukaryotic promoters share basic, highly conserved structure. This area does not evolve quickly because it is extremely important in DNA transcription. These promoters (in most cases) include a basic basal promoter like a TATA box, and enhancers that bind to transcription factors.
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During transcription of a eukaryotic cell, what determines the template strand?
The TATA box is found in the promoter region of the template strand. This TATA box serves as a signal for the initiation of translation of DNA into mRNA. The location of the promoter region and it's unique base sequence signals the start of the translation process.
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