gen-define-epigenetics-and-give-one-short-worked-example-16e1

Define epigenetics and give one short worked example.

# Epigenetics **Definition:** Epigenetics refers to heritable changes in gene expression that occur *without* alterations to the underlying DNA sequence. These changes involve chemical modifications to DNA or histone proteins that affect whether genes are turned "on" or "off." ## Short Worked Example: DNA Methylation in Honeybees **Scenario:** Genetically identical honeybee larvae develop into either queens or workers based solely on their diet. **Mechanism:** - **Larvae fed royal jelly** (rich diet) → Low DNA methylation on certain genes → These genes stay active → Development of queen characteristics (larger size, fertility, longer lifespan) - **Larvae fed worker jelly** (restricted diet) → High DNA methylation on the same genes → These genes are silenced → Development of worker characteristics (smaller size, sterility, shorter lifespan) **Key Point:** Same DNA sequence, but different epigenetic marks (methylation patterns) create dramatically different outcomes. The diet triggers chemical tags that control gene expression without changing the genetic code itself. This demonstrates how environmental factors (nutrition) can create stable, long-lasting changes in how genes function through epigenetic mechanisms.