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Questions and Answers
What type of cofactors do Type I restriction endonucleases require for their activity?
What type of cofactors do Type I restriction endonucleases require for their activity?
What is a distinguishing feature of the recognition sequences of Type I restriction endonucleases?
What is a distinguishing feature of the recognition sequences of Type I restriction endonucleases?
Which type of restriction endonucleases cleave DNA at nonspecific sites?
Which type of restriction endonucleases cleave DNA at nonspecific sites?
Which type of restriction endonucleases have separate enzymes for restriction and modification activities?
Which type of restriction endonucleases have separate enzymes for restriction and modification activities?
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What is the recognition site length for Type II restriction endonucleases?
What is the recognition site length for Type II restriction endonucleases?
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What is an advantage of Type II restriction endonucleases over Type I and III systems?
What is an advantage of Type II restriction endonucleases over Type I and III systems?
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Which of the following cofactors are required for the activity of Type II restriction endonucleases?
Which of the following cofactors are required for the activity of Type II restriction endonucleases?
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What is a key advantage of Type II restriction endonucleases over Type I and Type III enzymes in molecular biology techniques?
What is a key advantage of Type II restriction endonucleases over Type I and Type III enzymes in molecular biology techniques?
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Which type of DNA ends are produced by the restriction enzymes BamHI and EcoRI?
Which type of DNA ends are produced by the restriction enzymes BamHI and EcoRI?
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If a researcher wants to clone a gene into a plasmid vector, which type of restriction enzyme would be most suitable?
If a researcher wants to clone a gene into a plasmid vector, which type of restriction enzyme would be most suitable?
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Which of the following statements about Type II restriction endonucleases is NOT true?
Which of the following statements about Type II restriction endonucleases is NOT true?
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The recognition site for the restriction enzyme HindIII is represented by the sequence $5' : \overline{AAGCTT} : 3'$. What type of DNA ends would this enzyme produce upon cleavage?
The recognition site for the restriction enzyme HindIII is represented by the sequence $5' : \overline{AAGCTT} : 3'$. What type of DNA ends would this enzyme produce upon cleavage?
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What is a characteristic of Sticky 3’ ends produced by Type II Restriction Enzymes?
What is a characteristic of Sticky 3’ ends produced by Type II Restriction Enzymes?
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What is a distinguishing feature of Blunt ends produced by Type II Restriction Enzymes?
What is a distinguishing feature of Blunt ends produced by Type II Restriction Enzymes?
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What is a common characteristic between Sticky 5’ ends and Blunt ends produced by Type II Restriction Enzymes?
What is a common characteristic between Sticky 5’ ends and Blunt ends produced by Type II Restriction Enzymes?
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What is a disadvantage of Sticky ends produced by Type II Restriction Enzymes?
What is a disadvantage of Sticky ends produced by Type II Restriction Enzymes?
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What is a distinguishing feature of Type IV enzymes compared to Type I and III?
What is a distinguishing feature of Type IV enzymes compared to Type I and III?
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What is a characteristic of Sticky 5’ ends produced by Type II Restriction Enzymes?
What is a characteristic of Sticky 5’ ends produced by Type II Restriction Enzymes?
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Study Notes
Palindromic Sequence and Nomenclature
- Palindromic sequence refers to a type of DNA sequence that reads the same backward as forward.
- Restriction enzymes (RE) are used to cleave DNA at specific recognition sequences.
Types of Restriction Enzymes (REs)
- Type I REs: exhibit both restriction and DNA modification activities, require cofactors such as Mg2+ ions, Sadenosylmethionine (SAM), and ATP, and have a complex mechanism.
- Type II REs: have separate enzymes for restriction and modification, recognition site is 4-6 bp sequence, usually palindromic, and require only Mg2+ ions as cofactors.
- Type III REs: have a complex mechanism, require ATP and Mg2+ ions, and cleave DNA at sites 25-27 bp from recognition site.
- Type IV REs: require Mg2+ ions, and cleave close to or within recognition sequence.
Characteristics of Type II REs
- Recognition site: 4-6 bp sequence, usually palindromic.
- Cleavage: site-specific, hydrolyze specific phosphodiester bonds in both DNA strands.
- Cofactors: require only Mg2+ ions.
- Advantages: easier to use, widely used in molecular biology and recombinant DNA techniques.
Types of DNA Ends Produced by Type II REs
- Sticky ends: staggered ends with short, single-stranded overhangs.
- Sticky 5' ends: 5' overhang.
- Sticky 3' ends: 3' overhang.
- Blunt ends: straight cut, resulting in a flat pair of bases on the ends of the DNA.
Examples of Restriction Enzymes
- EcoRI: Type II RE, recognition site is 5' GAATTC 3', and produces sticky 5' ends.
- BamHI: Type II RE, recognition site is 5' GGATCC 3', and produces sticky 5' ends.
- HindIII: Type II RE, recognition site is 5' AAGCTT 3', and produces sticky 5' ends.
- Other examples: EcoB, EcoR, Sphl, HinfIII, Mrr, AluI, BalI, HaeIII, SmaI, ApaI, Arthrospira platensis NIES-39, Providencia stuartii ApII, PstI.
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Description
Test your knowledge on different types of restriction endonucleases, including Type I, II, III, and type III. Learn about the cleavage sites, cofactors, and examples of each type of restriction endonuclease.
