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Genome |
| The recent news of successful sequencing of human genome Human Genome Project has made international headlines. What is genome? How unlocking its mysteries benefit the mankind? |
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| Every organism, including humans, has a genome that contains all of the biological information needed to build and maintain a living example of that organism. The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes. |
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| You can visualize the DNA through the following diagram. |
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Human genome for example consists of 3 Billion base pairs (AT and CG) which are arranged in a sequence. The human genome has 46 Chromosomes consisting of 30,000 genes. |
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Only 25% of the human sequence identified is contained within genes (the coding DNA) and only about 2% of the genetic code contains information to produce proteins. So from 50-75% of the sequence is non-coding DNA or the "string" between the genes. The number of genes in humans and other organisms is quite similar. However, humans have on an average of three times as many kinds of proteins as the fly or worm. This is because the genetic code of the human genes can be read in a variety of ways, producing on average 3 proteins per gene compared to one protein per gene in the worm. |
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| So, why was it necessary to decode the entire sequence of all the 30,000 genes? |
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| Imagine two people Rita and Rebecca having gone to doctor to get treated for common cold. The doctor gives the same prescription to both of them. Rita recovers in few days, whereas Rebecca’s situation worsens. Why is that both having common cold reacted differently to the same medicine? |
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| The answer lies in genes. It has been found that human genome is 99.9% similar for all human beings. However, 0.1% of the human genome varies from individual to individual and this difference makes everyone of us unique. Of the 3 Billion sequences, 3 million is unique for every individual. This small difference is large enough to make people react to different substances (food, medicine) differently. |
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