During the Second World War there was a great famine in Holland. Luckily, many people survived the harsh conditions. Some were even pregnant during this period and gave birth to healthy children afterwards. But when they grew up something extraordinary happened. The generation of people born shortly after this famine was shown to have higher rates of coronary heart diseases and obesity. From one generation to the next, something had changed. This could not have been caused by a mutation in the genes, since such a large share of the people showed signs of this change. This observation is a great example of what we call epigenetics, a study that looks into how environment and individual lifestyle can influence gene expression. To put it differently, epigenetics is a field of study that concerns the characteristics, or genotype, that do not require changes in DNA. It describes how genes are passed on. To make it easier to understand one could compare (epi)genetics to something commonly used, such as a music player. Let us take Spotify for example. It contains every song that could be possibly played. These songs are the genes in a cell. Within Spotify you are able to choose certain playlist, artists or genres. These determine which of the many possible songs are going to be played. Hence, they are processes which determine which songs are expressed, just like epigenetics. Your body contains many different cell types, such as skin cells, muscle cells or liver cells. Every cell has a nucleus were the DNA is stored. The DNA in each cell holds information to express over 20,000 genes. One can easily conclude that to differentiate the cells from each other not all 20,000 genes should be expressed. Skin cells need the skin genes and liver cells need genes that concern information on the liver. This means that in every cell certain genes must be activated or deactivated. To understand how genes are activated or deactivated it is important to first understand what DNA looks like. Each cell in your body contains approximately 2 meters of DNA, which is the blueprint for our lives. It is tightly packed around certain proteins known as histones. This DNA-protein complex can regulate which genes are expressed in different cell types. The DNA is a molecule composed of two chains that rotate around each other forming a structure known as a double helix. The tow chains are linked together by nucleotides. There are four different nucleotides: cytosine (C), guanine (G), adenine (A) and thymine (T). These nucleotides are joined together according to base pairing rules (A with T and C with G) to link the two DNA chains.
DNA structure
Modifications
Epigenetics on female bees
Dit artikel is geschreven door Jochem Hak