A "microarray" is a tool used in genetic research to determine the mRNAs being produced in a particular tissue, and their relative level of expression. Known genes can therefore be assayed for their expression in different situations. One use of the technology is in cancer diagnosis and treatment. If a known gene functions as a tumour suppressor, predict which of the following pieces of evidence would be most useful in diagnosis of a cancer due to a mutation in this tumour-suppressor gene.
A) The tissue sample shows a high level of gene expression relative to a control (noncancerous) sample.
B) The tissue sample responds to treatment with a mitosis-promoting compound.
C) The mRNAs for the targeted tumour suppressor sequence are not being produced.
D) The mRNAs for cyclins and kinases show unusually high levels of expression.

Question

Quizplus · Accepted Answer

If the mRNAs for the targeted tumour suppressor sequence are not being produced, it suggests that there has been a mutation or other disruption in the gene that codes for that suppressor. This disruption could be responsible for causing the cancer, and its absence would be a strong indicator of the presence of the disease. A high level of gene expression (A) or expression of cyclins and kinases (D) might suggest a range of different situations and would not be as specific to the tumour-suppressor gene in question. Treatment with a mitosis-promoting compound (B) might suggest a more aggressive cancer, but it does not necessarily have a clear link to the tumour suppressor.

A "Microarray" Is a Tool Used in Genetic Research to Determine