Which of the following statements about restriction enzymes is correct?

Question

BlackTom AI · Accepted Answer

Question restatement: Which of the following statements about restriction enzymes is correct?

Options:
- There is only one known restriction enzyme, called EcoRI
- Restriction enzymes are short oligonucleotides for use in amplifying a specific region of DNA
- Restriction enzymes are only useful at detecting insertion/deletion polymorphisms
- Restriction enzymes are used to cut specific DNA sequences

Now, evaluate each option:

Option 1: 'There is only one known restriction enzyme, called EcoRI.' EcoRI is indeed a well-known restriction enzyme, but it is not the only one. In reality, hundreds of restriction enzymes from various bacterial species have been identified, each recognizing different DNA sequences. This makes the statement factually incorrect because it overgeneralizes to a single enzyme.

Option 2: 'Restriction enzymes are short oligonucleotides for use in amplifying a specific region of DNA.' This describes primers used in PCR, which are short primers or oligonucleotides. Restriction enzymes are enzymes that recognize and cleave DNA at specific sequences, not oligonucleotides used for amplification. Hence this statement confuses enzymes with primers and is incorrect.

Option 3: 'Restriction enzymes are only useful at detecting insertion/deletion polymorphisms.' While restriction enzymes can be used in techniques like RFLP to detect polymorphisms, their utility is not limited to insertion/deletion detection. They are broadly used to cut DNA at specific sequences for cloning, mapping, and DNA analysis. Restriction enzymes have many applications beyond detecting indels, so this statement is too narrow and inaccurate.

Option 4: 'Restriction enzymes are used to cut specific DNA sequences.' This statement accurately captures the fundamental role of restriction enzymes: they recognize particular DNA sequence motifs and introduce cuts at or near those sites. This is the core, well-established function of these enzymes in molecular biology, enabling cloning, plasmid preparation, and genome analysis.

Summary: By comparing the options, Option 4 best aligns with the canonical function of restriction enzymes. The other statements contain common misconceptions: the existence of only one enzyme, confusing enzymes with oligonucleotides used in amplification, and limiting their use to indel detection. Each incorrect option contains a specific factual error or oversimplification that misrepresents the enzyme’s role and capabilities.

Which of the following statements about restriction enzymes is correct?单项选择题

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