Question

1. Both miRNA and siRNA in eukaryotes and riboswitches inbacteria are capable of regulating gene expression. Explain twospecific differences in the mechanisms of miRNA/siRNA generegulation in eukaryotes and riboswitches in bacteria?

2. We are examining nucleotide substitutions in a histoneprotein gene and in a growth hormone gene in several species ofrodents. We observe that the ratio of nonsynonymous to synonymousnucleotide substitutions (Ka/Ks) is 0.1 for the histone proteingene, but is 1.5 for the growth hormone gene. For each gene, whatdoes this ratio tell us about evolution of these genes with regardto selection and neutrality? Give a brief explanation for eachanswer.