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Ch. 8 - Molecular Biology of Transcription and RNA Processing
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 8 - Molecular Biology of Transcription and RNA ProcessingProblem 5c
Chapter 8, Problem 5c

The following is a portion of an mRNA sequence:
3'-AUCGUCAUGCAGA-5'
Identify the direction in which the promoter region for this gene will be located.

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1
Understand that the mRNA sequence provided is written in the 3' to 5' direction, which is unusual because mRNA is typically written in the 5' to 3' direction. This means we need to reverse the sequence to analyze it properly.
Reverse the sequence to obtain the standard 5' to 3' orientation: 5'-AGACGUACUGCUA-3'. This is the correct orientation for interpreting the mRNA sequence.
Recall that the promoter region is located upstream of the transcription start site. In the context of the mRNA sequence, 'upstream' refers to the direction opposite to the synthesis of the mRNA strand.
Determine the direction of transcription. Since mRNA is synthesized in the 5' to 3' direction, the promoter region must be located upstream, which corresponds to the 5' end of the template DNA strand (or the 3' end of the mRNA sequence).
Conclude that the promoter region for this gene will be located in the direction corresponding to the 3' end of the provided mRNA sequence, as this is upstream relative to the transcription process.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

mRNA Directionality

mRNA is synthesized in the 5' to 3' direction, meaning that the 5' end of the mRNA corresponds to the start of the coding sequence. The sequence provided is in the 3' to 5' orientation, indicating that the actual coding sequence runs from the 5' end of the mRNA to the 3' end.
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Directionality

Promoter Region

The promoter region is a specific DNA sequence located upstream of a gene that initiates transcription. It is typically found at the 5' end of the coding sequence and is recognized by RNA polymerase and transcription factors, which bind to it to start the process of mRNA synthesis.
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Transcription Initiation

Transcription initiation is the first step in gene expression, where RNA polymerase binds to the promoter region and unwinds the DNA. This process determines the direction of transcription, which will always proceed from the promoter towards the 3' end of the template strand, thus establishing the orientation of the mRNA produced.
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Eukaryotic Transcription
Related Practice
Textbook Question

The diagram below shows a DNA duplex. The template strand is identified, as is the location of the nucleotide.

If this region is a eukaryotic gene transcribed by RNA polymerase III, where are the promoter consensus sequences located?

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Textbook Question

The following is a portion of an mRNA sequence:

3'-AUCGUCAUGCAGA-5'

During transcription, was the adenine at the left-hand side of the sequence the first or the last nucleotide used to build the portion of mRNA shown? Explain how you know.

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Textbook Question

The following is a portion of an mRNA sequence:

3'-AUCGUCAUGCAGA-5'

Write out the sequence and polarity of the DNA duplex that encodes this mRNA segment. Label the template and coding DNA strands.

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Textbook Question

Compare and contrast the properties of DNA polymerase and RNA polymerase, listing at least three similarities and at least three differences between the molecules.

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Textbook Question

The DNA sequences shown below are from the promoter regions of six bacterial genes. In each case, the last nucleotide in the sequence (highlighted in blue) is the nucleotide that initiates transcription. Examine these sequences and identify the Pribnow box sequence at approximately -10 for each promoter.

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Textbook Question

The DNA sequences shown below are from the promoter regions of six bacterial genes. In each case, the last nucleotide in the sequence (highlighted in blue) is the nucleotide that initiates transcription. Determine the consensus sequence for the Pribnow box from these sequences.

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