Genetic engineering/recombinant DNA technology

Genetic engineering/recombinant DNA technology This is DNA in which genes from two different sources, often different species are combined in vitro into the same molecule.

Genes from one organism are introduced into the genome of an unrelated organism.

Reminder:

Gene: the basic unit of inheritance; a length of DNA on a chromosome.

Genome: the complement of genes of an organism (or of a cell).

Genotype: the genetic constitution of an organism; genes acting together with environmental factors produce the organisms appearance (phenotype).

The genetic engineers tool kit of enzymes

Genetic engineering makes use of purified enzymes that enable DNA and RNA to be manipulated in precisely known ways.

EnzymeNatural sourcesApplication in recombinant DNA technology

Restriction enzymes (restriction endonucleases)Cytoplasm of bacteria combats viral infection by breaking up viral DNACuts/cleaves DNA molecules into shorter segments/fragments, at specific nucleotide sequences

DNA ligaseWith nucleic acid in nuclei of cells of all organismsJoins together DNA molecules during replication of DNA

PolymeraseWith nucleic acid in nuclei of cells of all organismsSynthesises nucleic acid strands from nucleotides, guided by a template strand of nucleic acid

Reverse transcriptaseFound in particular types of RNA viruses called retrovirusesSynthesises a DNA strand complementary to an existing RNA strand

PAGE 1