Final answer:
Prior to fertilization, the methylation status of the maternal and paternal genomes can differ. DNA methylation occurs within specific regions called CpG islands, which can lead to gene silencing. These methylation patterns can be influenced by environmental factors and can be inherited through epigenetic inheritance.
Step-by-step explanation:
Prior to fertilization, the methylation status of the maternal and paternal genomes can differ. DNA methylation occurs within specific regions called CpG islands, which are stretches of DNA with a high frequency of cytosine and guanine dinucleotide DNA pairs. Methylation of genes within these regions can lead to gene silencing. These methylation patterns can be influenced by environmental factors and can be inherited in a process called epigenetic inheritance.
For example, if a gene is silenced in the gametes of one parent due to methylation, it can be transmitted to the offspring in its silenced state. The methylation status of genes can also be influenced by factors such as parental diet.
The methylation of DNA interacts with changes in chromatin organization. Highly methylated regions with deacetylated histones are tightly coiled and transcriptionally inactive.