Ch. 17 - Recombinant DNA Technology

Klug - Essentials of Genetics 10th Edition

Klug10th EditionEssentials of GeneticsISBN: 9780135588789Not the one you use?Change textbook

Klug 10th Edition

Ch. 17 - Recombinant DNA Technology

Problem 9

Chapter 17, Problem 9

What are the advantages of using a restriction enzyme whose recognition site is relatively rare? When would you use such enzymes?

Verified step by step guidance

Understand that restriction enzymes cut DNA at specific recognition sites, which are short sequences of nucleotides. The frequency of these sites in a DNA molecule depends on the length and specificity of the recognition sequence.

Recognize that a restriction enzyme with a rare recognition site cuts DNA less frequently, resulting in fewer and larger DNA fragments compared to enzymes with common recognition sites.

Consider the advantage of using such enzymes: they produce larger fragments that can be useful for cloning large DNA segments, mapping genomes, or analyzing large structural features of DNA.

Identify scenarios where rare-cutting enzymes are preferred, such as when you want to isolate or study large genes, genomic regions, or when performing techniques like pulsed-field gel electrophoresis that separate large DNA fragments.

Summarize that rare-cutting restriction enzymes are valuable tools when the goal is to minimize the number of cuts and maintain larger DNA fragments for detailed genetic analysis or manipulation.

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Key Concepts

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

Restriction Enzymes and Recognition Sites

Restriction enzymes are proteins that cut DNA at specific sequences called recognition sites. These sites are usually short, palindromic sequences. The frequency of these sites in a genome depends on their length and sequence specificity, influencing how often the enzyme cuts the DNA.

Advantages of Rare Recognition Sites

Enzymes with rare recognition sites cut DNA less frequently, producing fewer and larger fragments. This is useful for cloning large DNA segments or when fewer cuts are needed to maintain the integrity of the DNA, reducing complexity in downstream analysis.

Applications of Rare-Cutting Restriction Enzymes

Rare-cutting enzymes are used in applications like constructing genomic libraries, mapping large DNA molecules, or preparing DNA for techniques requiring large intact fragments, such as pulsed-field gel electrophoresis or certain cloning strategies.

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Textbook Question

Restriction sites are palindromic; that is, they read the same in the 5' to 3' direction on each strand of DNA. What is the advantage of having restriction sites organized this way?

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Textbook Question

Using DNA sequencing on a cloned DNA segment, you recover the nucleotide sequence shown below. Does this segment contain a palindromic recognition sequence for a restriction enzyme? If so, what is the double-stranded sequence of the palindrome, and what enzyme would cut at this sequence?

CAGTATGGATCCCAT

Textbook Question

List the advantages and disadvantages of using plasmids as cloning vectors. What advantages do BACs and YACs provide over plasmids as cloning vectors?

Textbook Question

In a typical PCR reaction, describe what is happening in stages occurring at temperature ranges

(a) 92-26 °C

(b) 45-65 °C and

Textbook Question

In the context of recombinant DNA technology, of what use is a probe?

Textbook Question

If you performed a PCR experiment starting with only one copy of double-stranded DNA, approximately how many DNA molecules would be present in the reaction tube after 15 cycles of amplification?

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