EPIGENETICS

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Context

Epigenetics plays a critical role in human health by regulating gene expression without the direct modification of DNA sequence.

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About Epigenetics

It refers to the study of changes in gene expression that do not involve alterations to the underlying DNA sequence. These changes are influenced by various environmental and lifestyle factors and can have significant implications for health, development, and evolution.

Unlike genetic mutations, which alter the DNA sequence, epigenetic modifications affect how genes are turned on or off and can be reversible.

Mechanisms

• DNA Methylation: It involves the addition of a methyl group to the DNA molecule, typically at cytosine bases. DNA methylation usually suppresses gene expression by making the DNA less accessible to transcription machinery.
• Histone Modification: DNA in cells is wrapped around proteins called histones. Chemical modifications to these histones, such as acetylation and methylation, can alter how tightly DNA is wound around them. Tightly wound DNA is less accessible for gene transcription, effectively silencing those genes, while loosely wound DNA is more active.
• Non-coding RNA: Certain RNA molecules do not code for proteins but play a role in regulating gene expression at the transcriptional and post-transcriptional levels. For example, microRNAs can bind to messenger RNAs (mRNAs) and prevent them from being translated into proteins.

Role of Environment in Epigenetics

Epigenetics bridges the gap between genetics and environmental influences. Factors such as diet, stress, exposure to toxins, and lifestyle choices like smoking can lead to epigenetic changes that affect gene expression. For instance, studies on identical twins have shown that although they start with identical DNA and similar epigenetic marks at birth, their epigenetic profiles diverge over time due to different life experiences and environmental exposures.

Epigenetic Disorders

Epigenetic modifications can lead to various health conditions when gene regulation goes awry. Some disorders directly result from disrupted epigenetic marks, such as Beckwith-Wiedemann syndrome, an imprinting disorder. Other conditions, like certain cancers and neurological disorders (e.g., Alzheimer's disease), have been linked to epigenetic changes that affect gene expression patterns.

Epigenetics and Evolution

Epigenetics also plays a role in evolution and adaptation. In general, epigenetic variation is heritable and permits populations to quickly adapt to environmental changes without genetic variation. Thus, knowledge in epigenetics can provide new perspectives in understanding human diversity and how historical events shape subsequent generations.

Sources: Wikipedia