Most laboratory strains of E. coli contain site-specific DNA methylases. The methylase encoded by the dam gene (Dam methylase) transfers a methyl group from S-adenosylmethionine (SAM) to the N6 position of the adenine residues in the sequence GATC. The Dcm methylase (encoded by the dcm gene) methylates the internal cytosine residues in the sequences CCAGG and CCTGG at the C5 position. The E. coli strain used in this experiment is mutated so Dcm and Dam methylases are not functional. What is the advantage of using dcm or dam mutants when the E. coli will be a host to recombinant DNA? HINT – If the E. coli methylates the DNA in these cells, then how would this affect the activity of restriction endonucleases
Most laboratory strains of E. coli contain site-specific DNA methylases. The methylase encoded
by the dam gene (Dam methylase) transfers a methyl group from S-adenosylmethionine (SAM) to
the N6 position of the adenine residues in the sequence GATC. The Dcm methylase (encoded by
the dcm gene) methylates the internal cytosine residues in the sequences CCAGG and CCTGG at
the C5 position.
The E. coli strain used in this experiment is mutated so Dcm and Dam methylases are not
functional. What is the advantage of using dcm or dam mutants when the E. coli will be a host to
recombinant DNA? HINT – If the E. coli methylates the DNA in these cells, then how would this
affect the activity of restriction endonucleases
Molecular cloning is the process of making identical copies of a DNA molecule, which can be a gene, a fragment of a genome, or an entire genome. This technique is used to study and manipulate DNA in vitro, and it is essential for genetic engineering, biotechnology, and basic research.
One of the key tools in molecular cloning is restriction endonucleases, also known as restriction enzymes. These enzymes are found in bacteria and are used by them as a defense mechanism against invading viruses. They cut DNA at specific recognition sequences, producing fragments that can be separated and analyzed.
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