Genetic engineering

In the syllabus and the exam

Genetic engineering is the deliberate, technology-based transfer of a specific gene from one organism into another so that the recipient organism expresses a new, desired characteristic, and candidates are expected to describe the general steps involved: identifying and isolating the desired gene, usually using a restriction enzyme to cut it out of the donor organism's DNA, inserting that gene into a vector (commonly a bacterial plasmid) using a ligase enzyme, and introducing the vector into a recipient cell so it can be expressed. Candidates should be able to give real, syllabus-relevant applications, such as bacteria genetically engineered to produce human insulin for treating diabetes, or crop plants engineered for pest resistance or improved nutrient content, and to state a specific benefit tied to each named example rather than a vague claim that genetic engineering 'helps society'. A frequent error is confusing genetic engineering with selective breeding: selective breeding works only within a single species over many generations by choosing which existing individuals reproduce, while genetic engineering directly transfers a specific gene, often between completely different species, within a single generation. Candidates should also be able to state, in balanced terms, a concern raised about genetic engineering, such as uncertainty over long-term ecological effects of releasing engineered organisms, without overstating this as a proven certain harm. Candidates should also be able to name the specific enzymes used at each stage of the process, a restriction enzyme to cut DNA at a precise sequence and a ligase enzyme to join the cut gene into the vector, since exam diagrams frequently label these steps and ask candidates to identify the enzyme responsible for each one.

Example

Inserting the human gene for insulin into a bacterium allows the bacterium to produce human insulin, an example of genetic engineering used to manufacture medicine on a large scale.

Related terms

Genetically modified organism (GMO)BiotechnologyGene

Source:SRC-DSKP-EN