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Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers
Freeman - Biological Science 7th Edition
Freeman7th EditionBiological ScienceISBN: 9783584863285Not the one you use?Change textbook
All textbooksFreeman 7th EditionCh. 20 - The Molecular Revolution: Biotechnology, Genomics, and New FrontiersProblem 11
Chapter 20, Problem 11

Potato blight causes potato plants to shrivel and rot. The disease is caused by the pathogen Phytophthora infestans, infamous for its role in Ireland's Great Potato Famine in the mid-1840s. The disease can devastate crops during wet weather, sometimes leading to total crop loss. Researchers aim to use recombinant DNA methods to transfer blight resistance genes from resistant varieties into susceptible varieties of potato.Explain how restriction endonucleases and DNA ligase could be used to insert a potato blight resistance gene into a plasmid.

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1
Identify and isolate the gene responsible for blight resistance in a potato variety that is naturally resistant to Phytophthora infestans. This gene will be the segment of DNA that needs to be inserted into the susceptible potato variety.
Use restriction endonucleases to cut the DNA at specific recognition sites. These enzymes act as molecular scissors to cut both the DNA containing the blight resistance gene and the plasmid DNA at specific sequences, creating sticky ends or blunt ends.
Ensure that the restriction endonuclease used on the plasmid DNA is the same or compatible with the one used on the blight resistance gene. This compatibility is crucial for the next step, as it allows the ends of the DNA fragments to match up, facilitating the insertion of the blight resistance gene into the plasmid.
Mix the cut plasmid with the isolated blight resistance gene. The sticky or blunt ends of the plasmid DNA will pair with the complementary ends of the blight resistance gene, allowing them to align and attach to each other.
Use DNA ligase to seal the nicks in the sugar-phosphate backbone of the DNA, effectively 'gluing' the blight resistance gene into the plasmid. This recombination results in a recombinant plasmid that now carries the blight resistance gene.

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Key Concepts

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

Restriction Endonucleases

Restriction endonucleases, or restriction enzymes, are proteins that cut DNA at specific sequences, creating fragments with 'sticky' or 'blunt' ends. These enzymes are essential in molecular biology for gene cloning, as they allow scientists to precisely excise a gene of interest, such as a potato blight resistance gene, from a larger DNA molecule. By cutting both the target gene and the plasmid DNA with the same restriction enzyme, compatible ends are generated, facilitating the insertion of the gene into the plasmid.
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1a) Use Restriction Enzymes

DNA Ligase

DNA ligase is an enzyme that facilitates the joining of DNA strands together by forming phosphodiester bonds. After a resistance gene is inserted into a plasmid using restriction endonucleases, DNA ligase is used to seal the nicks in the sugar-phosphate backbone of the DNA. This process is crucial for creating a stable recombinant DNA molecule, which can then be introduced into host cells for further propagation and expression of the resistance gene.
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Step 1) Create Recombinant DNA

Recombinant DNA Technology

Recombinant DNA technology involves combining DNA from different sources to create new genetic combinations. In the context of inserting a potato blight resistance gene into a plasmid, this technology allows researchers to manipulate genetic material to enhance traits in organisms, such as disease resistance in crops. By using restriction enzymes and ligases, scientists can create plasmids that carry beneficial genes, which can then be introduced into susceptible potato varieties to improve their resilience against pathogens like Phytophthora infestans.
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Map of DNA-Based Technology Lesson
Related Practice
Textbook Question
Revolutionaries executed Nicholas II, the last czar of Russia, along with his wife and five children, the family physician, and about a dozen servants. Many decades later, a grave said to hold the remains of the royal family was discovered. Biologists were asked to analyze DNA from the bodies. If the remains of the family were in this grave, predict how similar the DNA fingerprints would be between the parents, the children, and the unrelated individuals in the grave.
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Textbook Question

One hypothesis for differences between humans and chimpanzees involves differences in gene regulation. A study using RNA-seq showed that the overall patterns of gene expression were similar in the liver and blood of the two species, but the expression patterns were strikingly different in the brain. How do these results relate to the hypothesis?

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Textbook Question

Potato blight causes potato plants to shrivel and rot. The disease is caused by the pathogen Phytophthora infestans, infamous for its role in Ireland's Great Potato Famine in the mid-1840s. The disease can devastate crops during wet weather, sometimes leading to total crop loss. Researchers aim to use recombinant DNA methods to transfer blight resistance genes from resistant varieties into susceptible varieties of potato. Explain how restriction endonucleases and DNA ligase could be used to insert a potato blight resistance gene into a plasmid.

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views
Textbook Question
Potato blight causes potato plants to shrivel and rot. The disease is caused by the pathogen Phytophthora infestans, infamous for its role in Ireland's Great Potato Famine in the mid-1840s. The disease can devastate crops during wet weather, sometimes leading to total crop loss. Researchers aim to use recombinant DNA methods to transfer blight resistance genes from resistant varieties into susceptible varieties of potato.Transgenic plants usually contain genes of bacterial plasmid origin. In a recent study, researchers designed a strategy that avoided using any plasmid genes. They transformed cells from a susceptible potato variety with a potato blight resistance gene cloned from a resistant variety. Next, to determine which plants from this group were also free of plasmid DNA (cloning vector) sequences, they performed PCR using primers specific for the plasmid. The positive control lane shows PCR amplification of plasmid DNA only, and the negative control lane shows an attempted PCR amplification of no added DNA. Based on the gel analysis of PCR products shown below, which plants contain only the potato gene? Explain your answer.
893
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Textbook Question

Potato blight causes potato plants to shrivel and rot. The disease is caused by the pathogen Phytophthora infestans, infamous for its role in Ireland's Great Potato Famine in the mid-1840s. The disease can devastate crops during wet weather, sometimes leading to total crop loss. Researchers aim to use recombinant DNA methods to transfer blight resistance genes from resistant varieties into susceptible varieties of potato. Transgenic plants usually contain genes of bacterial plasmid origin. In a recent study, researchers designed a strategy that avoided using any plasmid genes. They transformed cells from a susceptible potato variety with a potato blight resistance gene cloned from a resistant variety. Next, to determine which plants from this group were also free of plasmid DNA (cloning vector) sequences, they performed PCR using primers specific for the plasmid. The positive control lane shows PCR amplification of plasmid DNA only, and the negative control lane shows an attempted PCR amplification of no added DNA. Based on the gel analysis of PCR products shown below, which plants contain only the potato gene? Explain your answer.

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Textbook Question

If the sequence of DNA in Question 12 were amplified using 25 PCR cycles, then the amount of this DNA would be predicted to increase by          -fold.

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