The discoverers of the structure of DNA. It's very interesting book "The Double Helix" in which one of them tells how the discovery tube place, cutting molecule models in cardboard, and giving credence to the view of a chemist who insist that the structure of a nucleotide was not like was in all the books. Image taken from: http://www.caramutt.com/
Let
schematically how are usually performed DNA analysis:
When there is very little DNA, because the sample is small, the sample undergoes a process called "polymerase reaction chain", which copies many times as you want, a DNA sample, to have the amount needed. Then the DNA is purified, using a delicate and long, once purified and unwind, [1] you add a "restriction enzyme" that acts as a security key, search for DNA, and when he finds a particular sequence of nucleotides which "fits", reacts with it, and cut the DNA at that point, (this is done supposedly everywhere where it is the particular sequence that makes "couples" with the enzyme), it is understood that there are some DNA fragments that are repeated many times, next to each other along the DNA chain and has seen the number of these repeats varies from person to person. When DNA is cut into pieces, the fragments are measured, so if the DNA is the same, the pieces are cut the same size. And this, well summarized, is the method by which they usually do DNA analysis. [2]
not forget that if the DNA is something of an incredibly small size, their pieces are slightly smaller; and methods at our disposal to measure these fragments are not so precise that they can discern the size of a piece of DNA containing 112 repetitions (of the fragment that is repeated), the size of another fragment which has 109 repetitions. The two DNA give the same result in the analysis. [3]
Of course there are many people who have the same number of repetitions of these fragments, which you, or I, [4] so do not spend money on this type of evidence because see what happens:
When the FBI forensic laboratory, DNA analysis performed on blood samples of 225 agents, and repeated the tests a second time, with the same samples, in the same laboratories, and the analysis made by the best researchers, one in six outcomes, not equal out. [5]
One of the graphical representations of DNA analysis. Image taken from: http://hanniagomez.blogspot.com/
remember that DNA analysis does not give the specific sequence of nucleotides of DNA and gene associations with disease, we are continually listening the media have, removing very specific cases, the validity of the following example: For a time he thought he had identified a "gene" that was related to a manic-depressive disorder, until ill of this disorder, two people who had no such "gene manic-depressive." [6]
And if you, is that among 216 people with hemophilia B studied, they found that mutations that cause it are given in 115 different places in the DNA. [7] With so there is no way to know with clarity and sharpness, to what extent is crucial to have or not have a particular variation in a DNA fragment.
So despite the enormous economic interests are at stake in this matter of genes, in 1992, after a serious dispute between scientists on the validity or otherwise of the DNA evidence, an article appeared under the headline: "U.S. House seeks to restrict the use of DNA in court, "adding the subtitle:" You have asked the judges to discard the "DNA fingerprints" until they have a solid scientific basis. " [8]
And we have not said anything about the pollution: if you play with your fingers or coughs near a sample, contaminated with their own DNA.
If the FBI agents, and with the same analytical conditions, failed to identify the 16.7% of times, when it comes to comparing the DNA of a parent with your child which has half his DNA and the other half from the mother, how sure of success there?.
We told all this, because if so it goes with the living, why not go with the DNA of the dead, let alone if it is a Neanderthal, or bones, such as carrying 800,000 years Atapuerca ( according to his calculations) buried in the depths of a cave, wetting, breaking, deforming etc.
[1] DNA in its natural state, is meticulously folded and refolded on itself, forming the chromosomes.
[2] Hubbard, Ruth, and Wald, Elijah - "The myth of Gen" p. 250 and 251.
[3] Hubbard, Ruth, y Wald, Elijah Op. cit. p. 252.
[4] Lewontin, RC y Hartl, DL, "Population Genetics in DNA Forense Tiping" - Science - 254 p. 1.745 - 1750 to 1991.
Lander, Eric S. "DNA Fingerprinting on Trial" Nature - 339 - p. 501 - 505-1989.
[5] Lewontin, RC y Hartl, DL Op. cit.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 252.
[6] Kelsoe, John R. y al "Re-evaluation of the Linkage Relationship Between Chromosome 11 Loci's and the Gene for Bipolar Affective Disorder in the Old Order Amish" - Nature, - 342 p. 238 – 243.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 110.
[7] Gianelli, F. y al. “Haemophilia B.: Data Base of Point Mutations and Short Additions and Deletions” – Nucleic Acis Research – 18 – p. 4.053 – 4.059.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 107.
[8] Kolata, Gina “U.S. Panel Seeking Restricción on Use of DNA in Courts” – New York Times – 14 Abril – p. 1, C7 – 1.992.
When there is very little DNA, because the sample is small, the sample undergoes a process called "polymerase reaction chain", which copies many times as you want, a DNA sample, to have the amount needed. Then the DNA is purified, using a delicate and long, once purified and unwind, [1] you add a "restriction enzyme" that acts as a security key, search for DNA, and when he finds a particular sequence of nucleotides which "fits", reacts with it, and cut the DNA at that point, (this is done supposedly everywhere where it is the particular sequence that makes "couples" with the enzyme), it is understood that there are some DNA fragments that are repeated many times, next to each other along the DNA chain and has seen the number of these repeats varies from person to person. When DNA is cut into pieces, the fragments are measured, so if the DNA is the same, the pieces are cut the same size. And this, well summarized, is the method by which they usually do DNA analysis. [2]
not forget that if the DNA is something of an incredibly small size, their pieces are slightly smaller; and methods at our disposal to measure these fragments are not so precise that they can discern the size of a piece of DNA containing 112 repetitions (of the fragment that is repeated), the size of another fragment which has 109 repetitions. The two DNA give the same result in the analysis. [3]
Of course there are many people who have the same number of repetitions of these fragments, which you, or I, [4] so do not spend money on this type of evidence because see what happens:
When the FBI forensic laboratory, DNA analysis performed on blood samples of 225 agents, and repeated the tests a second time, with the same samples, in the same laboratories, and the analysis made by the best researchers, one in six outcomes, not equal out. [5]
One of the graphical representations of DNA analysis. Image taken from: http://hanniagomez.blogspot.com/ remember that DNA analysis does not give the specific sequence of nucleotides of DNA and gene associations with disease, we are continually listening the media have, removing very specific cases, the validity of the following example: For a time he thought he had identified a "gene" that was related to a manic-depressive disorder, until ill of this disorder, two people who had no such "gene manic-depressive." [6]
And if you, is that among 216 people with hemophilia B studied, they found that mutations that cause it are given in 115 different places in the DNA. [7] With so there is no way to know with clarity and sharpness, to what extent is crucial to have or not have a particular variation in a DNA fragment.
So despite the enormous economic interests are at stake in this matter of genes, in 1992, after a serious dispute between scientists on the validity or otherwise of the DNA evidence, an article appeared under the headline: "U.S. House seeks to restrict the use of DNA in court, "adding the subtitle:" You have asked the judges to discard the "DNA fingerprints" until they have a solid scientific basis. " [8]
And we have not said anything about the pollution: if you play with your fingers or coughs near a sample, contaminated with their own DNA.
If the FBI agents, and with the same analytical conditions, failed to identify the 16.7% of times, when it comes to comparing the DNA of a parent with your child which has half his DNA and the other half from the mother, how sure of success there?.
We told all this, because if so it goes with the living, why not go with the DNA of the dead, let alone if it is a Neanderthal, or bones, such as carrying 800,000 years Atapuerca ( according to his calculations) buried in the depths of a cave, wetting, breaking, deforming etc.
[1] DNA in its natural state, is meticulously folded and refolded on itself, forming the chromosomes.
[2] Hubbard, Ruth, and Wald, Elijah - "The myth of Gen" p. 250 and 251.
[3] Hubbard, Ruth, y Wald, Elijah Op. cit. p. 252.
[4] Lewontin, RC y Hartl, DL, "Population Genetics in DNA Forense Tiping" - Science - 254 p. 1.745 - 1750 to 1991.
Lander, Eric S. "DNA Fingerprinting on Trial" Nature - 339 - p. 501 - 505-1989.
[5] Lewontin, RC y Hartl, DL Op. cit.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 252.
[6] Kelsoe, John R. y al "Re-evaluation of the Linkage Relationship Between Chromosome 11 Loci's and the Gene for Bipolar Affective Disorder in the Old Order Amish" - Nature, - 342 p. 238 – 243.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 110.
[7] Gianelli, F. y al. “Haemophilia B.: Data Base of Point Mutations and Short Additions and Deletions” – Nucleic Acis Research – 18 – p. 4.053 – 4.059.
Hubbard, Ruth, y Wald, Elijah Op. cit. p. 107.
[8] Kolata, Gina “U.S. Panel Seeking Restricción on Use of DNA in Courts” – New York Times – 14 Abril – p. 1, C7 – 1.992.
Semogil 18 de Junio del 2.010
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