CAIE A Level Biology 9700 · Genetic technology
A research team is engineering a strain of yeast (Saccharomyces cerevisiae) to produce human insulin. They construct a plasmid containing the human insulin gene (chemically synthesized from its mRNA sequence) under a yeast promoter, and a separate gene for green fluorescent protein (GFP) also under a yeast promoter. Explain how the appearance of green fluorescent colonies confirms that the insulin gene has been taken up and expressed.
6 marks, so the mark scheme is looking for about 6 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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.