Advanced Placement (AP) Biology Practice Exam

DNA methylation is important for which of the following processes?

1. Cell division

2. Gene regulation

3. Protein synthesis

4. Cell signaling

The correct answer is: Gene regulation

DNA methylation is a critical epigenetic modification that plays a significant role in gene regulation. This process involves the addition of a methyl group to the DNA molecule, typically at cytosine bases in regions of the genome that are rich in cytosine and guanine, known as CpG sites. When methyl groups are added to DNA, they can inhibit the binding of transcription factors and other proteins necessary for gene expression, effectively silencing those genes. This regulation is crucial during various developmental stages, influencing cellular differentiation. Moreover, DNA methylation patterns can be inherited, contributing to heritable changes in gene expression without altering the underlying DNA sequence. Through these mechanisms, DNA methylation helps control which genes are active or inactive in a given cell type, allowing for the diverse functions and characteristics of different cell types within an organism. This makes gene regulation the primary and most relevant process associated with DNA methylation.