Genetic Modification
Genetic modification is carried out by gene transfer between species
- Genetic modification is a term usually used to refer to the transfer of DNA sequences from one species to another
- The key feature of the genetic code that makes this possible is that it is universal, meaning that almost every organism uses the same four nitrogenous bases – A, T, C & G. There are a few exceptions
- Additionally the same codons code for the same amino acids in all living things (meaning that genetic information is transferable between species)
- Thus scientists have been able to change an organism's DNA artificially by combining lengths of nucleotides from different sources (typically the nucleotides are from different species)
- If an organism contains nucleotide sequences from a different species it is called a transgenic organism
- DNA that has been introduced into the genome of another organism is called recombinant DNA (rDNA)
- Any organism that has introduced genetic material is a genetically modified organism (GMO)
- The mechanisms of transcription and translation are also universal which means that the transferred DNA can be translated within cells of the genetically modified organism
Recombinant DNA technology
- This form of genetic modification involves the transfer of fragments of DNA from one organism/species into another organism/species
- The resulting genetically modified organism will then contain recombinant DNA and will be a Genetically Modified Organism (GMO)
- Example
- A gene from the bacterium Bacillus thuringiensis (Bt for short) codes for a toxin that has insecticide properties
- This gene has useful properties in commercial maize plants (Zea mays), so has been transferred into transgenic maize plants to make them less susceptible to insect pests, improving agricultural productivity as a result
Illustration of a maize plant that has recombinant DNA (DNA from Bacillus thuringiensis)
Uses of genetic modification
- Because all genes code for proteins, useful proteins can be manufactured by the creating of transgenic organisms
- Some of the key uses of genetic modification include the genetic modification of:
- Crops to increase crop yield through resistance to drought, disease, pesticides and herbicides; or to provide increased nutritional value (e.g. golden rice)
- Livestock to give disease and pest resistance, increased productivity and new characteristics (eg. goats that produce milk containing spider silk)
- Bacteria to produce medicines e.g. insulin. Additionally bacterial can be modified to decompose toxic pollutants or carry out large scale chemical production
Analogy: Essay Writing and Recombinant DNA
- Creating transgenic organisms is rather like copying and pasting some text from one of your previous essays into the one that you are currently writing
- If you believe that the essay that you are currently writing can be strengthened by the use of some text from another essay that you have previously written, it is a common practice to use the computer’s copy and paste function to transfer text in one block without having to retype it
- This has similar features to genetic modification in the creation of a transgenic organism