Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

10. Transcription

Transcription in Eukaryotes

Genetics

10. Transcription

Transcription in Eukaryotes

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2:34 minutes

Problem 30a

Textbook Question

Genomic DNA from a mouse is isolated, fragmented, and denatured into single strands. It is then mixed with mRNA isolated from the cytoplasm of mouse cells. The image represents an electron micrograph result showing the hybridization of single-stranded DNA and mRNA.
Which nucleic acid is indicated by the 'a' pointer? Justify your answer.

Verified step by step guidance

Understand the context of the problem: The question involves hybridization of single-stranded DNA (ssDNA) and mRNA. Hybridization occurs when complementary nucleic acid strands bind to each other, forming a DNA-RNA hybrid.

Analyze the experimental setup: Genomic DNA is fragmented and denatured into single strands, while mRNA is isolated from the cytoplasm. The hybridization process allows mRNA to bind to complementary sequences in the ssDNA.

Interpret the electron micrograph: The 'a' pointer likely indicates a specific nucleic acid structure. In such experiments, regions of ssDNA that do not hybridize with mRNA remain as loops, while hybridized regions form double-stranded DNA-RNA hybrids.

Justify the identity of the nucleic acid: If the 'a' pointer is marking a loop, it represents single-stranded DNA (ssDNA) that does not have a complementary sequence in the mRNA. This occurs because introns (non-coding regions) in the genomic DNA are absent in the mRNA, which only contains exons (coding regions).

Conclude the reasoning: The 'a' pointer indicates single-stranded DNA (ssDNA) because it corresponds to intronic regions that are not transcribed into mRNA and therefore cannot hybridize with the mRNA.

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Key Concepts

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

Hybridization

Hybridization refers to the process where complementary nucleic acid strands bind together to form a double-stranded structure. In this context, single-stranded DNA from the mouse genome can hybridize with mRNA, which is complementary to the DNA sequence that was transcribed. This process is crucial for understanding how genetic information is expressed and can be visualized in experiments like the one described.

mRNA (Messenger RNA)

mRNA, or messenger RNA, is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. It is synthesized during transcription and serves as a template for translation. In the context of the question, the mRNA isolated from mouse cells is essential for understanding which specific sequences of DNA are being expressed in the cells.

Electron Micrography

Electron micrography is a technique that uses a beam of electrons to create high-resolution images of biological specimens. This method allows researchers to visualize the hybridization of nucleic acids at a molecular level. In the question, the electron micrograph provides visual evidence of the interaction between the single-stranded DNA and mRNA, helping to identify the nucleic acid indicated by the 'a' pointer.

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Related Practice

Textbook Question

The DNA sequence below gives the first 12 base pairs of the transcribed region of a gene, and the template and nontemplate strands of DNA are identified. The transcription start is the thymine nucleotide at the end of the sequence given. Use the diagram to answer the list of questions. Make a copy of the diagram before you begin answering the questions, or have one group member diagram the answers for bacteria and another group member diagram the answers for eukaryotes.

Nontemplate strand ___________ TTGCTACGGTCA___________

Template strand ___________ AACGATGCCAGT___________

Write the polarity of the two DNA strands shown.

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Textbook Question

Genomic DNA from a mouse is isolated, fragmented, and denatured into single strands. It is then mixed with mRNA isolated from the cytoplasm of mouse cells. The image represents an electron micrograph result showing the hybridization of single-stranded DNA and mRNA.

What term best identifies the nucleic acid region indicated by the 'd' pointer?

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Textbook Question

What term best identifies the nucleic acid region indicated by the 'c' pointer?

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Textbook Question

Which nucleic acid is indicated by the 'b' pointer? Justify your answer.

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Multiple Choice