Ch. 15 - Recombinant DNA Technology and Its Applications

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook

Sanders 3rd Edition

Ch. 15 - Recombinant DNA Technology and Its Applications

Problem 12

Chapter 15, Problem 12

Compare and contrast methods for making transgenic plants and transgenic Drosophila.

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Step 1: Define what transgenic organisms are—organisms that have had foreign DNA introduced into their genome to express new traits—and explain that both transgenic plants and Drosophila are created to study gene function or improve traits.

Step 2: Describe common methods for making transgenic plants, such as Agrobacterium-mediated transformation, where the bacterium Agrobacterium tumefaciens transfers a gene of interest into plant cells, and biolistic (gene gun) methods, which physically deliver DNA into plant cells.

Step 3: Explain methods for making transgenic Drosophila, focusing on microinjection of DNA directly into early embryos, often using P-element transposons to integrate the foreign DNA into the fly genome.

Step 4: Compare the two approaches by highlighting that plant transformation often relies on bacterial vectors or physical delivery due to plant cell walls, while Drosophila transformation uses direct embryo injection and transposon-mediated integration because of the animal’s developmental biology.

Step 5: Contrast the efficiency, technical challenges, and typical applications of each method, noting that plant transformation can be slower and requires tissue culture, whereas Drosophila transformation is relatively rapid but limited to certain genomic insertion sites.

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Key Concepts

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

Transgenic Plant Production Methods

Transgenic plants are commonly created using Agrobacterium-mediated transformation or biolistic (gene gun) methods. Agrobacterium transfers a DNA segment (T-DNA) into the plant genome, mainly effective in dicots, while biolistics physically delivers DNA into plant cells and can be used for monocots. Both methods require tissue culture to regenerate whole plants from transformed cells.

Transgenic Drosophila Production Methods

Transgenic Drosophila are typically generated by microinjecting DNA into early embryos, where the DNA integrates into the germline. Techniques include P-element mediated transformation, which uses transposons to insert DNA, and more recent methods like CRISPR/Cas9 for targeted genome editing. These methods allow stable inheritance of the transgene in fly populations.

Comparison of Transformation Techniques

While both plants and Drosophila require DNA integration into the genome, plant methods often rely on bacterial vectors or physical delivery and tissue culture regeneration, whereas Drosophila methods involve direct embryo injection and transposon-mediated insertion. Differences arise from organism biology, such as cell wall presence in plants and developmental stages accessible for transformation.

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Transformation

Related Practice

Textbook Question

In an inheritance case, a man has died leaving his estate to be divided equally between 'his wife and his offspring.' His wife (M) has an adult daughter (D), and they argue that they should split the estate equally. As a young couple, however, the man and his wife had a son that they gave up for adoption. Two men have appeared, each claiming to be the son of the couple and therefore entitled to a one-third share of the estate. The accompanying illustration shows the results of DNA analysis for five genes for the mother (M), her daughter (D), and the two claimants (S1 and S2). Do the DNA results suggest that either man is likely to be the son of the man and his wife? Explain.

Textbook Question

Injection of double-stranded RNA can lead to gene silencing by degradation of RNA molecules complementary to either strand of the dsRNA. Could RNAi be used in gene therapy for a defect caused by a recessive allele? A dominant allele? If so, what might be the major obstacle to using RNAi as a therapeutic agent?

Textbook Question

In an inheritance case, a man has died leaving his estate to be divided equally between 'his wife and his offspring.' His wife (M) has an adult daughter (D), and they argue that they should split the estate equally. As a young couple, however, the man and his wife had a son that they gave up for adoption. Two men have appeared, each claiming to be the son of the couple and therefore entitled to a one-third share of the estate. The accompanying illustration shows the results of DNA analysis for five genes for the mother (M), her daughter (D), and the two claimants (S1 and S2). How many nonmaternal DNA bands are shared by D and S1? By D and S2?

Textbook Question

Three independently assorting STR markers (A, B, and C) are used to assess the paternity of a colt recently born to a quarter horse mare. Blood samples are drawn from the mare, her colt, and three possible male sires (S₁, S₂, and S₃). DNA at each marker locus is amplified by PCR, and a DNA electrophoresis gel is run for each marker. Amplified DNA bands are visualized in each gel by ethidium bromide staining. Gel results are shown below for each marker. Evaluate the data and determine if any of the potential sires can be excluded. Explain the basis of exclusion, if any, in each case.

Textbook Question

Three independently assorting STR markers (A, B, and C) are used to assess the paternity of a colt recently born to a quarter horse mare. Blood samples are drawn from the mare, her colt, and three possible male sires (S₁, S₂, and S₃). DNA at each marker locus is amplified by PCR, and a DNA electrophoresis gel is run for each marker. Amplified DNA bands are visualized in each gel by ethidium bromide staining. Gel results are shown below for each marker. Calculate the PI and CPI based on these STR markers, using the following population frequencies: A₁₂ = 0.12, A₁₀ = 0.18; B₁₈ = 0.08, B₁₂ = 0.17; C₁₆ = 0.11, C₁₄ = 0.20.

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Textbook Question

It is often desirable to insert cDNAs into a cloning vector in such a way that all the cDNA clones will have the same orientation with respect to the sequences of the plasmid. This is referred to as directional cloning. Outline how you would directionally clone a cDNA library in the plasmid vector pUC18.