HSC · Topic explainer
Checking whether a transgene is expressed
Producing a transgenic organism requires introducing a DNA sequence and identifying organisms that carry it. Gene expression is a separate check. A suitable regulatory sequence can help drive transcription, and evidence of RNA or protein can show whether the introduced gene is expressed in the intended tissue.
Worked example
Imagine a mosquito engineered to make an introduced protein in its gut. First, use a DNA test to check for the inserted sequence in candidate insects. Then compare the presence of that protein in gut samples from candidates and unmodified controls.
A positive DNA test establishes presence of the sequence. A protein assay with an appropriate positive control can support expression. To establish the intended biological effect, add an experiment measuring the relevant outcome in modified and unmodified groups.
Official exam practice
Find other years and marking guidance in the Biology official exam archive.