5 facts that you probably didn’t know about the DNA

1 The genome is sequenced completed.

It is a myth that all the genome has been sequenced. There is still 10 percent of genome yet to be sequenced. The existing sequencing methods works by breaking the DNA strands into tiny pieces, sequencing them and reassembling the resulting “jigsaw”.

The main problem is that the middle and ends of chromosomes  are so repetitive that it is almost impossible to put it all back together.

2. Do the junk DNA even exist?

It was once believed that majority of our DNA was dismissed as junk, but now it is discovered as somewhat important. It still appears that 85 to 95 per cent of our DNA is indeed useless. While many part of DNA do not code for proteins they might have some function or other, the overall proportion of our DNA with a proven function remains tiny.

3. Now we can meet our ancestors

Do you want to know about your genetic roots?There are hundred of companies today who promise to  find distant relatives, or reveal family ties to such famous ancestors as Genghis Khan etc.

Most tests trace your maternal and paternal lines, by examining genetic markers on the mitochondrial DNA, which is passed from mother to child, or on the Y chromosome, passed from father to son. Like the roots of a tree, however, the genetic roots keep branching the deeper you look: tracing just two of these lines tells you nothing about all the others.

The companies also analyse the 22 pairs of non-sex chromosomes and report what percentage of an individual’s genome is of European, African, Native American or Asian origin

4. Information overload

Researchers are increasingly using software to predict what the DNA sequences do and trying to crack the codes that determines how the  RNAs are spliced or where in the cell RNAs get turned into proteins. In the end, though, there is no substitute for getting your hands dirty: the only way to be sure what a particular sequence does is to experiment with living cells and organisms.

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Now this is getting easier. Once a gene’s sequence is known, it is possible to switch off, or silence, that specific gene in living cells. So biologists are now systematically silencing genes in cells in dishes or in animals such as mice and fruit flies to see what happens.

5.The hunt for dark matter

Why is it proving so hard to pin point the genetic variations underlying common disorders, and what does the “dark matter” in the genome that accounts for this “missing heritability” consist of? Genetics are trying to find these stuffs out

Based on studies of diseases caused by a mutation in a single gene, such as sickle cell anaemia, some geneticists predicted that more complex conditions may be caused by a larger number of mutations in a series of genes. Each mutation would have a smaller effect, but collectively they would explain most of the heritability of the disease.

It is hoped that this would lead to ways to treat or prevent these diseases.

The original article was published in New scientist

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