CAIE A Level Biology 9700 · Genetic technology
A researcher wants to insert a human gene for a fluorescent protein into E. coli bacteria so that the bacteria produce the fluorescent protein. The researcher isolates the human gene using restriction enzymes and then uses DNA ligase to insert it into a plasmid. However, the researcher finds that the bacteria do not produce any fluorescent protein. Explain why it is necessary to transfer a promoter along with the gene when constructing the recombinant plasmid.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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