Gene Technology/ Genetic Engineering

 Background

  • The term 'genetic engineering' was first coined by Jack Williamson in his science fiction novel Dragon's Island, published in 1951.

  • The double-helix structure of Deoxyribonucleic acid (DNA) molecules is confirmed by James Watson and Francis Crick in 1953.

  • In 1972 Paul Berg used restriction enzymes and DNA ligases to create the first recombinant DNA molecules. 

  • The process of transferring genes from one organism to another, was first accomplished by Herbert Boyer and Stanley Cohen in 1973.

    • The first genetically modified organism to be created was a bacterium, in 1973.

    • In 1974, the same techniques were applied to mice.

    • In 1994 the first genetically modified foods were made available.

Key Terminology

Gene Technology

  • It is the application of the gene technique called genetic engineering, it includes self-cloning and deletion as well as cell hybridization.


Genetic Engineering

  • It is a technique by which heritable material, which does not usually occur or will not occur naturally in the organism or cell concerned, generated outside the organism, or the cell is inserted into said cell or organism.

  • It  also means the formation of new combinations of genetic material by incorporation of a cell into a host cell, where they occur naturally (self-cloning) as well as modification of an organism or in a cell by deletion and removal of parts of the heritable material.


Genetic Modification (GM)

  • It is the process whereby a genetically modified organism is made in the laboratory. 

    • This involves making artificial or modified genetic material (GM constructs) which are inserted into the genomes of cells or embryos.

    • The cell or embryo is regenerated to an organism.


Genome 

  • The totality of all the genetic material (deoxyribonucleic acid or DNA) in an organism, organised in a precise, though by no means fixed or constant way.

  • In the case of viruses, most of them will have ribonucleic acid or RNA as the genetic material.


Genes/ DNA

  • The gene is the basic physical unit of inheritance. These are passed from parents to offspring and contain the information needed to specify traits. They are arranged, one after another, on structures called chromosomes. 

    • A chromosome contains a single, long DNA molecule, only a portion of which corresponds to a single gene. Humans have approximately 20,000 genes arranged on their chromosomes.

    • Deoxyribonucleic acid (DNA): DNA is the chemical name for the molecule that carries genetic instructions in all living things. It is the central information storage system of most animals and plants, and even some viruses. 

      • The DNA molecule consists of two strands that wind around one another to form a shape known as a double helix. 

      • Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases--adenine (A), cytosine (C), guanine (G), and thymine (T). 

      • The two strands are held together by bonds between the bases; adenine bonds with thymine, and cytosine bonds with guanine. 

      • The sequence of the bases along the backbones serves as instructions for assembling protein and RNA molecules.




RiboNucleic Acid (RNA)

  • Similar to DNA except for the sugar in the nucleotide unit, which is ribose, instead of deoxyribose, and the base Uracil instead of Thymine. RNA is the genetic material for RNA viruses,

  • RNA editing:The process in which the base sequence of the RNA transcript is changed by addition of bases to the RNA molecule or by chemical transformation of one base to another. This subverts the genetic information carried in the genes.

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