Final answer:
When CpG islands are unmethylated, gene expression occurs and the genes in the unmethylated CpG islands can be transcribed and translated into proteins.
Step-by-step explanation:
When CpG islands are unmethylated, it means that the cytosine member of the CG pair does not have a methyl group attached to it. This lack of methylation allows for gene expression, meaning the genes in the unmethylated CpG islands can be transcribed and translated into proteins. Unmethylated CpG islands are associated with active gene expression and are commonly found in normal cells.