THE MOLECULAR BASIS OF INHERITANCE
RECOMBINANT DNA
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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sticky ends
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blunt ends
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no ends
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the ends
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Detailed explanation-1: -Purified DNA fragments are ligated into M13 RF DNA, which has been digested with SmaI to yield blunt-ends and dephosphorylated. M13 derived plasmids (pUC and pGEM-Z) and phagemids (Bluescript) are also used as sequencing vectors.
Detailed explanation-2: -SmaI is an isoschizomer of XmaI. SmaI produces blunt-ended fragments whereas XmaI produces a 5´ extension.
Detailed explanation-3: -SmaI cleaves between the internal CpG to produce blunt end scissions whereas XmaI cleaves between the external cytosines to produce a four base, five prime overhang. Each of the endonucleases forms stable, specific complexes with DNA in the absence of magnesium.
Detailed explanation-4: -In blunt ends, both strands are of equal length – i.e. they end at the same base position, leaving no unpaired bases on either strand. The concept is used in molecular biology, in cloning, or when subcloning insert DNA into vector DNA.
Detailed explanation-5: -The restriction enzyme that produces blunt ends is-EcoRV is a type II restriction endonuclease isolated from certain strains of Escherichia coli. It has the alternative name Eco32I. It creates blunt ends.