Northern blotting, RT-PCR, and microarrays can be used to analyze gene expression. A lab studies yeast cells, Comparing their growth in two different sugars, glucose and galactose. One student is comparing expression of the gene HMG2 under the different conditions. Which technique(s) could he use and why? Another student wants to compare expression of all the genes on chromosome 4, of which there are approximately 800. What technique(s) could she use and why?