Based on what you know about eukaryotic chromosomes and genes why do researchers choose to isolate mrna rather than DNA

The isolation of mRNA is always a good practice in molecular biology because it contains the first expression of a gene.

Explanation:

To example the statement above you can imagine what a cell can do to response to a stress like lack of energy. There might be some molecular mechanism that the cell itself is programmed to respond in this particular environment of poor nutrients. The genome of that particular cell might content various forms to respond to this particular scenario, however the transcription of a certain molecule of mRNA that is produced on that particular scenario is the possible right answer that the cell is programmed to respond. In order to understand how a cell respond to certain scenarios (like lack of energy) researchers isolate the answer of the genome, which is the product of transcription, the mRNA. Some other process like repression of genes might disturb the understanding of the mechanism of gene expression, however after you can identify and isolate the mRNA of your interest it can open certain possibilities in research area like measure the quantity of mRNA in a certain tissue and in a certain period of time a particular gene is expressed with tools like the real time PCR.