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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: 9780135564172당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 15a

The eukaryotic gene Gen-100 contains four introns labeled A to D. Imagine that Gen-100 has been isolated and its DNA has been denatured and mixed with polyadenylated mRNA from the gene.
Illustrate the R-loop structure that would be seen with electron microscopy.

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Understand the concept of R-loops: R-loops are structures formed when a single-stranded RNA hybridizes with its complementary DNA strand, displacing the other DNA strand. This occurs during transcription when mRNA pairs with the template strand of the gene.
Identify the structure of the Gen-100 gene: The gene contains four introns (A, B, C, and D) and exons in between. Introns are non-coding regions that are spliced out of the mRNA, while exons are coding regions that remain in the mature mRNA.
Visualize the hybridization process: When the denatured DNA of Gen-100 is mixed with the polyadenylated mRNA, the mRNA will hybridize with the complementary DNA strand (the template strand). The exons in the mRNA will align with their corresponding regions in the DNA, while the introns will form loops because they are absent in the mRNA.
Illustrate the R-loop structure: The R-loop will consist of double-stranded regions where the mRNA is hybridized to the template DNA strand, and single-stranded loops corresponding to the introns (A, B, C, and D) that are not present in the mRNA. These loops will be visible under electron microscopy as protrusions.
Label the R-loop diagram: Clearly label the exons (aligned regions), the intron loops (A, B, C, and D), and the polyadenylated tail of the mRNA. This will help in understanding the relationship between the gene's DNA and its processed mRNA.

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주요 개념

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R-loop Structure

An R-loop is a three-stranded nucleic acid structure formed when RNA hybridizes with a complementary DNA strand, displacing the non-template DNA strand. In the context of eukaryotic genes, R-loops can occur when mRNA binds to the DNA template, creating a loop that includes the coding sequence and excludes introns. This structure is significant for understanding gene expression and the processing of pre-mRNA.
추천 영상:
가이드 코스
03:49
Ribosome Structure

Introns and Exons

Introns are non-coding sequences within a gene that are transcribed into pre-mRNA but are removed during RNA splicing, while exons are the coding sequences that remain in the mature mRNA. The presence of introns allows for alternative splicing, which can generate multiple protein variants from a single gene. Understanding the distinction between introns and exons is crucial for interpreting the R-loop structure in the context of gene expression.
추천 영상:
가이드 코스
08:39
mRNA Processing

Polyadenylated mRNA

Polyadenylated mRNA refers to messenger RNA that has a poly(A) tail added to its 3' end, which is important for mRNA stability, export from the nucleus, and translation efficiency. In the context of the question, the polyadenylated mRNA from the isolated gene Gen-100 would hybridize with the corresponding DNA, facilitating the formation of the R-loop structure. This characteristic is essential for understanding the interaction between mRNA and DNA during gene expression.
추천 영상:
가이드 코스
08:39
mRNA Processing
관련 실천
교과서 질문

For a eukaryotic gene whose transcription requires the activity of an enhancer sequence, explain how proteins bound at the enhancer interact with RNA pol II and transcription factors bound at the promoter.

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교과서 질문

Three genes identified in the diagram as A, B, and C are transcribed from a region of DNA. The 5'-to-3' transcription of genes A and C elongates mRNA in the right-to-left direction, and transcription of gene B elongates mRNA in the left-to-right direction. For each gene, identify the coding strand by designating it as an 'upper strand' or 'lower strand' in the diagram.

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교과서 질문

The eukaryotic gene Gen-100 contains four introns labeled A to D. Imagine that Gen-100 has been isolated and its DNA has been denatured and mixed with polyadenylated mRNA from the gene.

Are intron regions single stranded or double stranded? Why?

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교과서 질문

Draw a bacterial promoter and label its consensus sequences. How does this promoter differ from a eukaryotic promoter transcribed:

By RNA polymerase II?

By RNA polymerase I?

By RNA polymerase III?

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교과서 질문

The segment of the bacterial TrpA gene involved in intrinsic termination of transcription is the following:

3'-TGGGTCGGGGCGGATTACTGCCCCGAAAAAAAACTTG-5'

5'-ACCCAGCCCCGCCTAATGACGGGGCTTTTTTTTGAAC-3' Draw the mRNA structure that forms during transcription of this segment of the TrpA gene.

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교과서 질문

The eukaryotic gene Gen-100 contains four introns labeled A to D. Imagine that Gen-100 has been isolated and its DNA has been denatured and mixed with polyadenylated mRNA from the gene.

Label the introns.

587
views