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Ch. 20 - Recombinant DNA Technology
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All textbooksKlug 12th EditionCh. 20 - Recombinant DNA TechnologyProblem 18

Chapter 19, Problem 18

To estimate the number of cleavage sites in a particular piece of DNA with a known size, you can apply the formula N/4ⁿ where N is the number of base pairs in the target DNA and n is the number of bases in the recognition sequence of the restriction enzyme. If the recognition sequence for BamHI is GGATCC and the  phage DNA contains approximately 48,500 bp, how many cleavage sites would you expect?

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Hi, everybody. Let's take a look at this practice problem together. What will the total number of cleavage sites in 38,400 base pair long D N A which is digested by the enzyme A L U L. The recognition sequence for A L U L is A G C T. Assume that all four nucleotides are present in equal proportions is the answer. A 50 B 100 C 150 or D 200 from the information in the question, we should deduce that the enzyme Aloul is a restriction enzyme. How do we know that recall that a restriction enzyme recognizes specific sequences and cleaves at those sites? This is what the enzyme A L U L does. Therefore, how do we calculate the total number of cleavage sites? You will need to know a formula in order to answer this question. And that formula is the following where the total number of cleavage sites Is equal to capital N divided by 4 to the little end power. Now capital N stands for the number of base pairs in the D N A sequence. Little N is the number of bases in the recognition sequence. So let's solve our formula here. We have big N over four to the little power. Capital N is the length of base pair or the number of base pairs in DNA which is 38, divided by four to the little power. Now, our recognition sequence recall is a G C T which means that there are four bases in the recognition sequence. Therefore, we will have four to the 4th power Solving this equation. We have 38,400 divided by 256 equals 150. Therefore, the correct answer will be option C- 150. Alright, everybody, I hope you found this helpful and I'll see you soon for the next practice problem.
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Textbook Question

Although the capture and trading of great apes has been banned in 112 countries since 1973, it is estimated that about 1000 chimpanzees are removed annually from Africa and smuggled into Europe, the United States, and Japan. This illegal trade is often disguised by simulating births in captivity. Until recently, genetic identity tests to uncover these illegal activities were not used because of the lack of highly polymorphic markers (markers that vary from one individual to the next) and the difficulties of obtaining chimpanzee blood samples. A study was reported in which DNA samples were extracted from freshly plucked chimpanzee hair roots and used as templates for PCR. The primers used in these studies flank highly polymorphic sites in human DNA that result from variable numbers of tandem nucleotide repeats. Several offspring and their putative parents were tested to determine whether the offspring were 'legitimate' or the product of illegal trading. The data are shown in the following Southern blot.

Examine the data carefully and choose the best conclusion.

a. None of the offspring are legitimate.
b. Offspring B and C are not the products of these parents and were probably purchased on the illegal market. The data are consistent with offspring A being legitimate.
c. Offspring A and B are products of the parents shown, but C is not and was therefore probably purchased on the illegal market.
d. There are not enough data to draw any conclusions. Additional polymorphic sites should be examined.
e. No conclusion can be drawn because 'human' primers were used. <>

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Textbook Question
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Variable number tandem repeats (VNTRs) are repeating DNA sequences of about 15–100 bp in length, found both within and between genes. Why are they commonly used in forensics?
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The National Institutes of Health created the Genetic Testing Registry (GTR) to increase transparency by publicly sharing information about the utility of their tests, research for the general public, patients, health-care workers, genetic counselors, insurance companies, and others. The Registry is intended to provide better information to patients, but companies involved in genetic testing are not required to participate. Should company participation be mandatory? Why or why not? Explain your answers.

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Should the FDA regulate direct-to-consumer genetic tests, or should these tests be available as a 'buyer beware' product?

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