Recombinant DNA & Genetic Engineering
Biology: Cambridge International A Level, topic 19.1.1
Principles of Genetic Engineering
Recombinant DNA is where fragments of foreign DNA are inserted into other sections of DNA.
Universal code
- DNA is made from a sequence of four bases (A, T, C, G).
- Every organism uses the four bases as the genetic code to produce proteins.
- This means that DNA can be considered a universal code.
Recombinant DNA
- The fact that the genetic code is universal means that any section of DNA can be taken from one organism and placed inside another.
- Once the DNA has been inserted, it is then transcribed and translated to produce proteins.
- Transcription and translation are also universal processes.
- The process of transferring sections of DNA produces recombinant DNA.
Fragments
- The sections of DNA that are transferred are called fragments.
- The organism that has received fragments of DNA is said to be transgenic.
Uses
Recombinant DNA has a variety of applications. These applications can be hugely beneficial in combating a number of humanitarian issues. These include:
Genetically modified crops
- Recombinant DNA can be used to genetically modify crops to improve their yield.
- Traits that can be improved include -
- Resistance to disease.
- Tolerance to the application of herbicides and pesticides.
- Tolerance of adverse environmental conditions (e.g. drought).
Genetically modified livestock
- Recombinant DNA can be used by farmers to make the production of meat more economically viable.
- Traits that can be improved include -
- Grow faster and larger.
- Resistance to disease.
Increased nutritional value
- Recombinant DNA can be used to increase the nutritional value of food.
- E.g. Rice has been genetically modified to contain Vitamin A. Vitamin A is a common deficiency in Asian countries where rice is widely consumed.
Treating diseases
- Recombinant DNA can be used to produce medicine and hormones to treat diseases.
- E.g. Individuals with type I diabetes used to be given pig insulin to control their blood sugar levels. Now human insulin is created using genetically modified bacteria.
Industry
- Recombinant DNA can be used to manufacture enzymes.
- These enzymes can be used in industry.
- E.g. Rennet is an enzyme traditionally taken from the stomach of young mammals like calves to produce cheese. It is now possible to make rennet using genetically engineered bacteria.
Test yourself on Recombinant DNA & Genetic Engineering
Which of the following statements about DNA fragments are true?
What is the name given to DNA that is produced from the transferring sections of DNA between organisms?
Which of these is NOT a trait that could be improved in genetically modified livestock?