✍️Notes on Biotechnology

Recombinant DNA technology

Genetic engineering, a kind of biotechnology, is the latest branch in applied genetics dealing the alteration of the genetic makeup of cells by deliberate and artificial means. Genetic engineering involves transfer or replacement of genes, so also known as recombination DNA technology or gene splicing.

Tools of genetic engineering:

(1) Two enzymes used in genetic engineering are restriction endonuclease and ligases.

(2) R.E. is used to cut the plasmid as well as the foreign DNA molecules of specific points while ligase is used to seal gaps or to join bits of DNA.

(3) The ability to clone and sequence essentially any gene or other DNA sequence of interest from any species depends on a special class of enzymes called restriction endonucleases.

(4) Restriction endonucleases are also called as molecular scissors or ‘chemical scalpels’.

(5) Restriction endonucleases cleave DNA molecules only at specific nucleotide sequence called restriction sites.

(6) The first restriction enzyme identified from a bacterial strain is designated I, the second II and so on, thus, restriction endonuclease EcoRI is produced by Escherichia coli strain RY 13.

(7) Restriction enzyme called EcoRI recognizes the sequence.

(8) It then cleaves the DNA between G and A on both strands. Restriction nucleases make staggered cuts; that is, they cleave the two strands of a double helix at different joints and blunt ended fragments; that is, they cut both strands at same place.