• Explain Why DNA Methylation Does Not Change Its Nucleotide Sequence.

Epigenetics is the study in the field of genetics, that examines heritable changes in gene expression in organisms (active versus inactive genes) that doe not involve changes in the underlying DNA sequence. This means a change in phenotype occurs, which changes the observable characteristics of an organism, while the genotype of the organisms stays the same. Although, epigenetic changes are regular and naturally occurring, other factors can influence the phenotype of an organism. Some of these factors include age, environment, and disease. However, these factors can cause physical modifications to the DNA and its associated structures, which result in altered functions.

1. What is DNA methylation? Explain why DNA methylation does not change its nucleotide sequence.

DNA methylation is an epigenetic mechanism used by cells to control gene expression. This mechanism is a commonly used epigenetic tool
The primary goal of the experiment was to test whether periconceptional exposure to famine (individuals conceived during the famine) was associated with differences in IGF2 DMR methylation in adulthood. The exposed individuals in the experiment were compared with their same sex siblings to measure the methylation of five CpG dinucleotides sites. It was observed that all CpG sites but one of the five were significantly less methylated among periconceptionally exposed individuals; the average methylation fraction was 0.515 among unexposed siblings compared to a fraction of 0.488 among exposed siblings. Concluding that periconceptional exposure to famine was connected to a 5.2% average lower methylation. Whereas, when observing individuals with late gestational exposure (individuals born in or shortly after the famine) it was found that late exposure did not affect DNA methylation in adulthood, but these individuals had the same methylation as unexposed