Restriction enzymes sticky ends

Sticky ends. After digestion of a DNA with certain restriction enzymes, the ends left have one strand overhanging the other to form a short (typically 4 nt) single-stranded segment. This overhang will easily re-attach to other ends like it and become known as sticky ends. ... 

As the second educt (B), the plasmid ONA with complementary sticky ends is prepared separately. In the first step the isolated plasmid DNA is cut open by a special type of enzyme called restriction endonuclease. It scans along the thread of DNA and recognizes short nucleotide sequences, e.g., CTGCAG, which ate cleaved at a specific site, e.g., between A and G. Some 50 of such enzymes are known and many are commercially available. The ends are then again extended witfa he aid of a terminal transferase by a short sequence of identical nucleotides complementary to the sticky ends of educt (A). 

This activity is intended to be performed in conjunction with Experiment 66. Restriction endonucleases, or restriction enzymes, cleave DNA at specific base sequences, fragmenting the DNA into smaller pieces. The two strands of a DNA double helix are cleaved at different places, resulting in uneven fragments called sticky ends. Cleavage of DNA by restriction enzymes is a required first step in various types of DNA analysis, including DNA fingerprinting and recombinant DNA technology. 

Restriction enzymes are sequence-specific in that they cut DNA at specific locations along the nucleotide chain. While some of these enzymes yield "blunt" ends to the resulting DNA fragment, others make staggered cuts in the DNA chain to produce "sticky" ends. Over 250 restriction enzymes are now commercially available. 

Cloning would not be possible without restriction enzymes. DNA chains with a "sticky" end act like molecular "Velcro", thereby enabling two pieces of DNA with complementary nucleotide sequences to be joined together. The linking of the DNA strands is brought about by the enzyme DNAligase which permanently joins the assembled DNA sequences with covalent bonds, thereby producing a recombinant DNA molecule. 

By contrast, other restriction enzymes cut at different portions of a DNA molecule, forming an "offset" break with "sticky" ends. For example, the restriction enzyme known as BamHI cuts between two GG nitrogen bases, but at different parts of the DNA molecule, forming "overhangs or sticky ends. These sticky ends provide locations at which new nitrogen base sequences can be inserted. 

This oligonucleotide contains sequences for one or more restriction sites, and after digestion with the proper restriction enzyme, the whole molecule will now have the proper sticky ends. 

Sticky ends are on strands that are cleaved unevenly that allow the formation of recombinant DNA when they are cleaved by the same restriction enzyme because the ends match. 

The cloning and manipulation of genes usually depends upon the precise cutting of DNA into discrete fragments by restriction endonucleases. Many restriction enzymes generate cohesive ends (sticky ends). Thus, EcoRI produces DNA fragments with the single-stranded "tails" shown here at the 5 -ends of the cut duplexes ... 

Restriction enzyme An enzyme that cuts DNA at a specific sequence leaving a complimentary sticky end. ... 

Hung, M. C., and Wensink, P. C. (1984). Different Restriction Enzyme-Generated Sticky DNA Ends Can Be Joined in Vitro. Nucleic Adds Res 12 1863. 

DNA ligase repairs broken DNA by joining two nucleotides in a DNA strand. It is commonly used in genetic engineering to do the reverse of a restriction enzyme that is, to join together complementary restriction fragments. While sticky ends allow two complementary restriction... 

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