Epigenetics might be a term you've come across, or perhaps it's new to you. In this post, we'll delve into the world of epigenetics, and by the end, you'll have a clear grasp of what this intriguing concept entails.
Let's start by explaining our DNA with a little bit of mathematics. There are about 3 billion pairs of DNA within each of our cells. I mean having an ATCG base pairing, and giving that each base is about 0.6 nanometers in length, then the total length is about 1.8 meters to about 2 meters of DNA when multiplied by 3 billion.
Now, DNA is not just a static entity; it's highly structured, organized, and dynamic. Its structure can undergo changes influenced by various factors. Before exploring these changes, it's crucial to comprehend how DNA is structured. Initially, DNA wraps around proteins called histones, forming structures known as nucleosomes or chromatin. Histones, carrying a positive charge, and DNA, carrying a negative charge, are held together by electrostatic attraction. A nucleosome consists of 9 histones with DNA coiled twice around an 8-histone core. These compressed layers of chromatin further organize to create chromosomes.
While chromatin are compressed, there are some that are tightly repressed while some are opened. It is important to know that the more tightly packaged a DNA chromosome is into a nucleus, the less accessible the DNA sequence becomes. Since DNA holds our information it might be difficult to initiate specific information. For instance, our DNA holds information for Transcription which is the initial stage of gene expression and for this to occur, specific information would be needed to initiate the command at the right place and for this to happen, the chromatin packaging is needed to influence what the cell does, how the command would be initiated, and what cell is going to perform this action.
Here's where Epigenetics comes into play. It refers to heritable information present on or in addition to the genomic sequence that can be altered. While epigenomes don't modify the DNA sequence itself, they determine whether certain genes are expressed. Epigenetics involves studying a person's genes over an extended period, observing changes and exploring whether these genes can be passed down to future generations.
While there are billions of cells in the body with each containing billions of DNA which have the exact same blueprint of the genetic code, there is the need for instruction from Methyl groups which binds to the gene telling it not to express the gene. They are also controlled by histones which can change how tightly or loosely the DNA is tied around them. Every cell has a distinct methylation and histone pattern and this is what gives them their matching orders.
Epigenetic tags are not static; they change over time and dictate which genes get expressed. For instance, during puberty, certain methyl groups attach to specific genes, prompting them to express the genetic code for puberty. The epigenome can undergo changes throughout our lives, triggered by activities and environmental factors such as our diet, smoking habits, alcohol consumption, and stress levels.
Epigenetics unveils the intricate layer of information atop our genetic sequence, showcasing how external factors influence gene expression. Going through life, our choices and environments can shape the epigenome.
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