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DNA ends refer to the properties of the ends of linear DNA molecules, which in molecular biology are described as "sticky" or "blunt" based on the shape of the complementary strands at the terminus. In sticky ends , one strand is longer than the other (typically by at least a few nucleotides), such that the longer strand has bases which are ...
Restriction enzymes can generate a wide variety of ends in the DNA they digest, but in cloning experiments most commonly-used restriction enzymes generate a 4-base single-stranded overhang called the sticky or cohesive end (exceptions include NdeI which generates a 2-base overhang, and those that generate blunt ends). These sticky ends can ...
EcoRI digestion produces "sticky" ends, whereas SmaI restriction enzyme cleavage produces "blunt" ends: Recognition sequences in DNA differ for each restriction enzyme, producing differences in the length, sequence and strand orientation (5' end or 3' end) of a sticky-end "overhang" of an enzyme restriction. [31]
Double stranded adapters are different from linkers in that they contain one blunt end and one sticky end. [ 1 ] For instance, a double stranded DNA adapter can be used to link the ends of two other DNA molecules (i.e., ends that do not have "sticky ends", that is complementary protruding single strands by themselves).
Sticky ends of DNA however are more likely to successfully bind with the help of a DNA ligase because of the exposed and unpaired nucleotides. For example, a sticky end trailing with AATTG is more likely to bind with a ligase than a blunt end where both the 5' and 3' DNA strands are paired. In the case of the example the AATTG would have a ...
DNA ligase can ligate complementary sticky and blunt ends, but blunt-end ligation is inefficient and requires a higher concentration of both DNA and DNA ligase than the ligation of sticky ends does. [6] For this reason, most restriction enzymes used in DNA cloning make staggered cuts in the DNA strands to create sticky ends.
Taq polymerase has a nontemplate-dependent terminal transferase activity that adds a single deoxyadenosine (A) to the 3'-end of the PCR products. This characteristic is exploited in "sticky end" TOPO TA cloning. [1] For "blunt end" TOPO cloning, the recipient vector does not have overhangs and blunt-ended DNA fragments can be cloned.
Blunt ends and sticky ends are relevant when ligating multiple DNA molecules, e.g. in restriction cloning, because sticky-ended molecules will not readily anneal to each other unless they have matching overhangs; blunt-ended molecules do not anneal in this way, so special procedures must be used to ensure that fragments with blunt ends are ...