a) Scientists genetically engineered some fish so they contained a green fluores
ID: 276788 • Letter: A
Question
a) Scientists genetically engineered some fish so they contained a green fluorescent protein (gfp) gene that made them glow green. They introduced the gene construct shown below into freshly fertilised egg cells promoter and regulatory region gfp coding sequence ATG TAG (1) What is a 'coding sequence' and what is the role of the ATG and TAG sequences shown? (2 marks) (ii) The scientists wanted the fish to express the gfp gene and glow green only when they are in water contaminated with heavy metals, so they could use them as pollution indicators. How could they do this? (2 marks) (ii) As a control the scientists wanted to engineer other fish that expressed the gfp (2 marks) gene and glowed green all the time. How could they do this? (iv) Would you expect every cell in the genetically engineered fish to contain the gfp gene? Give a reason for your answer. (2 marks) (v) Describe a method the scientists could use to confirm that the modified fish contain the gfp gene. (2 marks)Explanation / Answer
i) coding sequence- this part is responsible for protein expression. ATG is start codon, where translation starts and TAG is a stop codon, where translation ends.
ii) when fish which can express gfp gene in water, gfp can express if the scientists could make the design in such way that heavy metals can bind to promoter and regulatory region and this binding will induce if thegfp expression.
iii) if the gfp gene is under the control of a constitutively active promoter, then it will express gfp gene all the time and the fish will glow green and can be used as control.
iv) The number of cells which will express gfp gene will depend on the transfection efficiency of the gfp construct on the fertilized egg cell.
v) fish which express gfp gene can be identified and distinguished by fluroscence microscopy.
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