HEALTH & WELNESS -SECTION – APRIL

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How is “Beautiful” of DNA

All humans belong to the same species, so basically all human DNA is the same. The variation between races accounts for a tiny proportion of the DNA in the human genome.

What is not generally realized is that a huge proportion of people who would generally regard themselves as ‘white’ have at least one black ancestor in the last four generations (as demonstrated by random sampling of DNA in the population). Being simply ‘black’ or ‘white’ is based on only a tiny number of genes concerned with skin color. In most cases, skin color is also linked to a number of other genes which determine other characteristics – blood type, nose shape, etc but these are not fixed just to the skin color genes. More overall variation could be found, for example, between a white, blond, blue-eyed Icelander and an olive-skinned, brown-eyed Greek both of who would regard themselves as ‘white’. Genetically speaking, skin color is meaningless – it really is what goes on inside that counts.

The most beautiful of DNA :

Human genetic variation is the genetic differences both within and among populations. There may be multiple variants of any given gene in the human population (genes), leading to polymorphism. Many genes are not polymorphic, meaning that only a single allele is present in the population: the gene is then said to be fixed.

No two humans are genetically identical. Even monozygotic twins, who develop from one zygote, have infrequent genetic differences due to mutations occurring during development and gene copy number variation. Differences between individuals, even closely related individuals, are the key to techniques such as genetic fingerprinting. Alleles occur at different frequencies in different human populations, with populations that are more geographically and ancestrally remote tending to differ more.

Causes of differences between individuals include the exchange of genes during meiosis and various mutational events. There are at least two reasons why genetic variation exists between populations. Natural selection may confer an adaptive advantage to individuals in a specific environment if an allele provides a competitive advantage. Alleles under selection are likely to occur only in those geographic regions where they confer an advantage. The second main cause of genetic variation is due to the high degree of neutrality of most mutations. Most mutations do not appear to have any selective effect one way or the other on the organism. The main cause is genetic drift, this is the effect of random changes in the gene pool. In humans, founder effect and past small population size (increasing the likelihood of genetic drift) may have had an important influence in neutral differences between populations. The theory that humans recently migrated out of Africa supports this.

The study of human genetic variation has both evolutionary significance and medical applications. It can help scientists understand ancient human population migrations as well as how different human groups are biologically related to one another. For medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in people from specific geographic regions. New findings show that each human has on average 60 new mutations compared to their parents. Apart from mutations, many genes that may have aided humans in ancient times plague humans today. For example, it is suspected that genes that allow humans to more efficiently process food are those that make people susceptible to obesity and diabetes today. Courtesy of Wikipedia.com

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