The yeast and worms, simple biological evolution is how to birds and mammals such complex biological? A study conducted comparative genomics research shows, widely the answer to the problem may be hidden in the biological waste deoxyribonucleic acid (DNA). The scientists found that the more complex biological and its carrying the junk DNA, and the more they didn't code "useless" DNA help higher evolution of the complex.
Since the first eukaryotes -- including from yeast to human nuclei creatures -- since to be interpreted genome, scientists have wanted to know why, most of the DNA and no biological form useful genes. From the chromosome mutation protection to support structure for the so-called junk DNA could explain a lot of. But last year from humans, mice and rats of identical about junk DNA results show that in this area are important may include the regulating mechanism, which can control the basic biological chemical reactions and development process, this will help evolution of a more complicated. Compared with simple eukaryotes, complex organisms have more genes mutating will undoubtedly the greatly strengthened the fact that this one.
In order to this problem by a deeper understanding of the university of California, Santa cruz, UCSC (David) calculation biologists Haussler research group, a leading to 5 kinds of vertebrates -- people, rats, mice, chicken and the junk DNA sequences blowfish, with four insects, two worms and seven kinds of yeast junk DNA sequences are compared. Researchers from the result of an astonishing mode: the more complex and more important to junk DNA.
The possibility of implicit in different kinds of creatures, if you have the same DNA, so these will DNA is used to solve some key problems. The yeast and vertebrate sharing a certain amount of DNA, after all, they all need to manufacture protein, but only 15% of DNA and gene were not. Study group on July 14 of the human genome research magazine reported online, they will be more complicated with yeast compares the worms, and the latter is a multicellular organisms found that there was no 40% of the DNA encoding. Then, researchers will again be vertebrates and insects, and compares these creatures are more complex than the worms, and found that, there were more than 66% of DNA contains any code of DNA.
Participate in the research work of Adam biologists Siepel UCSC calculation, the research results about the worm, which is seriously need for them because scientists just two genomes are analyzed. Nonetheless, or think, this Siepel strongly support that such a theory that vertebrates and increase the complexity of biological insects is mainly due to genetic regulation of fine mode
2008年11月22日星期六
Modern plasmid DNA separation
Modern plasmid DNA separation and purification of separation from escherichia coli, since big represented in e. (E.c oli) and molecular biology, from the important status in the E.c oli separation and purification qc Piasmid < > become DNA DNA in recent years over an important topic of centrifugal technology. But the plasmid DNA separation and purification of super fast and centrifugal equipment (speeding centrifuge, turn and accessory) put forward higher request.
E.c oli is typical of prokaryote cells, due to lack of its nuclear prokaryote cells that have cell membranes of the unit can be separated with multiple functions for the components of the regional and local independent system, thus not endometrial cells contain nuclei (nuclear, organelles endoplasmic reticulum, golgi apparatus, body, the lysosome, etc.). Electron micrograph E.c oli two can show the difference between internal areas -- the cytoplasm and nuclear, in their around a layer of thinner outside the plasma membrane and very thick in the cell walls, and some end external attached of free flagellum. Plasmid DNA located in nuclear zone, filaments exist, such filaments in many cases is material very long annular DNA fragments of the secret that folded.
On the microstructure E.c oli to point, the super centrifugal separation and purification plasmid DNA sequence is before the pretreatment of:
E.c oli to use lysozyme, surfactants used to cell Trit, such as SDS X - 100, acetic acid, etc EE membrane pot that DNA, RNA and protein most sedimentation (90%).
Sediment can add TE buffer 10m (MTris - lmMEDTA pH8.0), HCL in - after the protein, and advances to go RNA, Can also be used to protein, speed centrifugation (level, to go to the RNA DNA or DNA fragments.
The plasmid DNA separation method of speeding.
The traditional separation method: a few years ago by equipment, plasmid DNA restriction of general use CsCl balance, separated from forming gradient centrifugation, density. With 10 ~ 12ml single capacity, for example, in turn, sling flat 36.000 RPM separated by 60 hours with Angle type head, 45, separation, the former inter OOOrpm 36 hours, including deceleration share to 1.3 billion of life, the latter to drive to use to 1 million to drive, the ministry of life at speed centrifuge total lifespan of 100 to 200 million each turn, undoubtedly, plus high cost experiment, the price of your CsCl dosage, make this type of factors such as the separation and purification of experimental work become very expensive.
E.c oli is typical of prokaryote cells, due to lack of its nuclear prokaryote cells that have cell membranes of the unit can be separated with multiple functions for the components of the regional and local independent system, thus not endometrial cells contain nuclei (nuclear, organelles endoplasmic reticulum, golgi apparatus, body, the lysosome, etc.). Electron micrograph E.c oli two can show the difference between internal areas -- the cytoplasm and nuclear, in their around a layer of thinner outside the plasma membrane and very thick in the cell walls, and some end external attached of free flagellum. Plasmid DNA located in nuclear zone, filaments exist, such filaments in many cases is material very long annular DNA fragments of the secret that folded.
On the microstructure E.c oli to point, the super centrifugal separation and purification plasmid DNA sequence is before the pretreatment of:
E.c oli to use lysozyme, surfactants used to cell Trit, such as SDS X - 100, acetic acid, etc EE membrane pot that DNA, RNA and protein most sedimentation (90%).
Sediment can add TE buffer 10m (MTris - lmMEDTA pH8.0), HCL in - after the protein, and advances to go RNA, Can also be used to protein, speed centrifugation (level, to go to the RNA DNA or DNA fragments.
The plasmid DNA separation method of speeding.
The traditional separation method: a few years ago by equipment, plasmid DNA restriction of general use CsCl balance, separated from forming gradient centrifugation, density. With 10 ~ 12ml single capacity, for example, in turn, sling flat 36.000 RPM separated by 60 hours with Angle type head, 45, separation, the former inter OOOrpm 36 hours, including deceleration share to 1.3 billion of life, the latter to drive to use to 1 million to drive, the ministry of life at speed centrifuge total lifespan of 100 to 200 million each turn, undoubtedly, plus high cost experiment, the price of your CsCl dosage, make this type of factors such as the separation and purification of experimental work become very expensive.
Appraisal parenthood
Appraisal parenthood currently use most of the DNA of identification. Is A person's blood, hair, saliva, oral cells can be used in parent-child etc., is very convenient. One of the 23 chromosomes (46), the same chromosome the same position as a pair of genetic alleles, usually one from the father, and from the mother. A If a DNA test to the site, a mother alleles, another can be the same with the father, or a question.
Using DNA in parent-child identification, just as ten to dozens of DNA test, if all sites, can be used to determine if a child, above 3 different sites, exclude parenthood, one or two different sites, should consider the gene mutations can do some sites, plus the check. DNA parent-child relationship, the accuracy of negation parent-child relationship, nearly 100% accuracy of the child reaches got.
DNA tests of common problem child identification
What is the child of DNA tests identified?
DNA (deoxyribonucleic acid) is personal cells in the body of the atomic matter. Each atom is 46 chromosomes, in addition, men and women's eggs sperm cells, each with 23 chromosomes, when sperm and egg combination. This 46 atomic chromosome is a life, therefore, each from his inherited half of molecules, and the other half from birth place.
DNA parent-child appraisal test and the traditional blood test is quite different. It may be in different samples, including blood tests on the cheek, cells, tissue cells cavity sample and semen samples. Due to blood types, such as A type, type B, type O or RH type, in the crowd, used to distinguish comparison of every man, but not valid identification of DNA tests child. Besides, the real twins each DNA is unique because it is so unique. Like fingerprint identification, child, used to be the most effective method of DNA. Our results are usually required than court accurate 10 to 100 times.
The identification of the parent accuracy
DNA parent-child appraisal is the most accurate identification method, if the child QinQuan genetic loci and tested the man (at least 1) sites, so the man inconsistent and 100% excluded, namely consanguinity absolutely impossible, he is the father of the child. If children and parents are the sites, we can draw the possibility of greater QinQuan relations, namely that got the kinship relations between them kiss.
Parent: (1) was identified notice shall be designated by the mother - the son - suspicious father or the parents and children - father or mother only two people generally not accepting JianDingZhe, (2) per adult consent to be identified, 12 years of teenagers should be appropriate to the identification of the opinion, (3) by expert should know his near relatives or any genetic history, (4) age generally identified children aged in half as well, (5) amniotic fluid or fluffy for pregnant women and suspected child appraisal shall be signed by identifying the father aggrement.
Using DNA in parent-child identification, just as ten to dozens of DNA test, if all sites, can be used to determine if a child, above 3 different sites, exclude parenthood, one or two different sites, should consider the gene mutations can do some sites, plus the check. DNA parent-child relationship, the accuracy of negation parent-child relationship, nearly 100% accuracy of the child reaches got.
DNA tests of common problem child identification
What is the child of DNA tests identified?
DNA (deoxyribonucleic acid) is personal cells in the body of the atomic matter. Each atom is 46 chromosomes, in addition, men and women's eggs sperm cells, each with 23 chromosomes, when sperm and egg combination. This 46 atomic chromosome is a life, therefore, each from his inherited half of molecules, and the other half from birth place.
DNA parent-child appraisal test and the traditional blood test is quite different. It may be in different samples, including blood tests on the cheek, cells, tissue cells cavity sample and semen samples. Due to blood types, such as A type, type B, type O or RH type, in the crowd, used to distinguish comparison of every man, but not valid identification of DNA tests child. Besides, the real twins each DNA is unique because it is so unique. Like fingerprint identification, child, used to be the most effective method of DNA. Our results are usually required than court accurate 10 to 100 times.
The identification of the parent accuracy
DNA parent-child appraisal is the most accurate identification method, if the child QinQuan genetic loci and tested the man (at least 1) sites, so the man inconsistent and 100% excluded, namely consanguinity absolutely impossible, he is the father of the child. If children and parents are the sites, we can draw the possibility of greater QinQuan relations, namely that got the kinship relations between them kiss.
Parent: (1) was identified notice shall be designated by the mother - the son - suspicious father or the parents and children - father or mother only two people generally not accepting JianDingZhe, (2) per adult consent to be identified, 12 years of teenagers should be appropriate to the identification of the opinion, (3) by expert should know his near relatives or any genetic history, (4) age generally identified children aged in half as well, (5) amniotic fluid or fluffy for pregnant women and suspected child appraisal shall be signed by identifying the father aggrement.
dna
In the 1950s, DNA double helix structure have been elucidated, opened a new chapter of life science, science and technology, new era. Then, the molecular mechanism of genetic copy, the genetic code -- DNA genetic information transmission center, as a rule, the basic unit of the genetic blueprint of cell engineering and gene and gene expression is one of the regulation. Thus, people have fully realize the fate of all creatures mastery of DNA, and it is contained in the genes, biological evolution process and the process of life, is different because of different operational track and DNA.
Know the major function and value of DNA, life scientists first thought can in some and closely related to the interests of the human nature in the iron break the law, heredity gene come to school in people with the purpose, treating the genetic fragments from different sources ", "to create new grafting new quality... so, with a full allure of science fiction miraculously become a reality. It happened in the early 1970s.
This scientific technology is miracle. DNA restructuring In 1972, American scientists Paul? The first successful restructuring, the first batch of DNA molecules in the world, marks the DNA restructuring technology -- genetic engineering as modern biology engineering foundation, become the modern biotechnology and life science foundation and the core.
Recombinant DNA techniques of concrete content is using artificial means different sources of a particular gene DNA fragments to restructure, change biology gene types and specific genes as a result of high science and technology.
Came late 1970s, because the engineering bacteria and DNA and have engineering properties of post-processing, genetic engineering or genetic engineering as DNA restructuring synonymous with technology is widely used. Now, genetic engineering, include the genome sequence analysis, nucleic acid molecular evolution analysis, molecular immunology, gene cloning, genetic diagnosis and gene therapy, etc. Say, DNA founded nearly 30 years restructuring technology to the great achievements obtained by the people have the incredible fantastic science, won the world of human life and preventing and treating illnesses open secrets "box" key.
Currently, DNA restructuring technology has many achievements. Recombinant DNA of the 20th century, to the largest technology applications in medicine, including active protein and vaccine peptide, the production, the disease occurrence mechanism, diagnosis and treatment of separation, new genes and environment monitoring and purification.
Many active peptides and proteins with treatment and prevention of diseases, they are from the corresponding gene. But due to the organization cells, so using yield a conventional methods to get enough for the clinical application.
Genetic engineering is a breakthrough in the limitations, to this kind of peptides and proteins, we have successfully produced in the treatment of diabetes and schizophrenia, leukemia and some insulin resistance of cancer therapeutic entity for treatment of disease, dwarf -- interferon human growth hormone therapy acromegaly and acute pancreatitis suppression of growth hormone release of product factor etc.
Genetic engineering can also will live on the DNA into the antigen such microbes by microorganisms, immunological stress in the host body growth can produce as weak, poison and stimulate doses of antigen long duration. Currently developing genetic engineering vaccine had dozens of many aspects, in dealing with leprosy coli bacteria are against e., pertussis, neisseria gonorrhoeae ShuangQiuJun etc, meningitis, In dealing with hepatitis a virus is for hepatitis b, cytomegalovirus,, herpes simplex, influenza, HIV vaccine... etc. China hepatitis b carriers and hepatitis b patients 1200 million, this situation as more Chinese scientists spurred by successfully developed hepatitis b vaccine made great social benefits and economic benefits.
Antibodies are the body's immune system is one of the main weapon disease resistance, founded in the 1970s monoclonal antibody technique in preventing disease-resistant aspects though plays an important role, but because it is difficult to achieve single RenYuan sex resistance, single resistance in the clinical application of limited. To solve this problem, in recent years, scientists using DNA restructuring technology has gained RenYuan sexual antibody, the antibody can guarantee the antigen and specificity and loyalty, and ensure the normal functions. Currently, there are many such antibodies in clinical trials, such as the resistance of single RenYuan special genetic marker, known as her2 breast cancer has entered the resistance test, Ⅲ period of single resistance RenYuan IGE Ⅱ has entered the period of treatment of asthma experiment.
Antibiotics in the treatment of the disease has played an important role in increasing Numbers, with antibiotics, with traditional methods and new antibiotic that chance. In order to obtain more new antibiotic, using DNA restructuring technology has become an important means of. People have won dozens of genetic engineering "heterozygous" for the clinical application of antibiotic, opening a new treatment.
As noted above mentioned gene engineering peptide, protein, vaccines, antibiotics, not only in drug prevention and control effectively avoid disease, but in some aspects in traditional method is also often similar drugs, thus producing more people.
Human diseases are directly or indirectly related with genes, at the genetic level on the diagnosis and treatment of disease, can achieve diagnostic accuracy of the etiology and primitivism, and can make the diagnosis and treatment of work to high sensitivity and specificity, convenient quickly. Gene level in diagnosis and treatment in professional called gene diagnosis and gene therapy. Currently genetic diagnosis as the fourth generation of clinical diagnosis technology has been widely applied to genetic diseases, cancer, cardiovascular and cerebrovascular diseases, virus disease and parasitic disease germs such diagnosis, And the object of gene therapy is through DNA restructuring specific functions of the technology to create a genetic recombination, to make up for lost, the function of genes, and to increase or a correction or abnormal cells.
In theory, gene therapy is ZhiBen cured without any adverse effects of therapy. However, although has more than 100 international gene therapy scheme is in clinical trials, but the gene therapy in theory and technology of some problems still make this treatment from the large scale application and a long distance. Whether the gene causes or implementation of genetic diagnosis, gene therapy, research mechanism, the disease is the key to understand the prerequisites for specific diseases related gene. With the human genome project ", "the scientists to human genes will get all the comprehensive understanding, which is formed by genetic restructuring to human health technology to create the conditions.
However, though genetic technology to human shows its fantastic "magic" as the charm, but also has a large number of scientists to this technology development and ecological ethic evolution to the human nature impact showed great concern. Theoretically, this technology is to make the development of a perfection of human have created any life forms or never had the ability of biology. People can imagine how this will be the result?
Scientists in DNA found outside the genetic code unless the new password
According to reports, the United States and Taiwan, they have Israeli scientists believe in DNA (to liu, except the genetic code) found outside the second password. New password for decision -- namely nuclear body of DNA protein surrounded by the position (--. The reel and protection and control of the way to DNA itself.
The findings could open, if that higher rates of relevant control mechanism of genetic information. For example, every kind of human cells to activate the genes needed, but can't touch other kinds of genes, used by cells is the key and mysterious process.
The institute of w) stuffed with America, northwestern university of Wisconsin meal and colleagues in the issue of "natural" scientific journals in writing, described the new password DNA.
Each individual cells are engaged in SanQianWanGe nuclear body. The nuclei are needed so much, because each line of DNA coated paper. Only a nuclear body, each DNA contains hundred units of a spiral of chromosomes, and a single DNA molecules in length may have as a unit 225 million.
Biologists have suspected for years, some of the DNA, especially those most easily bend DNA, may be more advantageous than other position of nuclear, but overall pattern is not obvious. Nowadays, dr wylton liger and analyzed approximately 200 position within the yeast gene sequence, these are both known nuclear body intertwined, they found a really exist hidden.
Through the understanding of this model, their successful predictions about five other organisms nucleation body position. This model is more easily bend can make DNA, and close the bag check two sequences. But in this mode, every body position of nuclear intertwine only several sequence, so it doesn't appear. Because of its formation conditions are loose and therefore does not conflict with the genetic code.
Know the major function and value of DNA, life scientists first thought can in some and closely related to the interests of the human nature in the iron break the law, heredity gene come to school in people with the purpose, treating the genetic fragments from different sources ", "to create new grafting new quality... so, with a full allure of science fiction miraculously become a reality. It happened in the early 1970s.
This scientific technology is miracle. DNA restructuring In 1972, American scientists Paul? The first successful restructuring, the first batch of DNA molecules in the world, marks the DNA restructuring technology -- genetic engineering as modern biology engineering foundation, become the modern biotechnology and life science foundation and the core.
Recombinant DNA techniques of concrete content is using artificial means different sources of a particular gene DNA fragments to restructure, change biology gene types and specific genes as a result of high science and technology.
Came late 1970s, because the engineering bacteria and DNA and have engineering properties of post-processing, genetic engineering or genetic engineering as DNA restructuring synonymous with technology is widely used. Now, genetic engineering, include the genome sequence analysis, nucleic acid molecular evolution analysis, molecular immunology, gene cloning, genetic diagnosis and gene therapy, etc. Say, DNA founded nearly 30 years restructuring technology to the great achievements obtained by the people have the incredible fantastic science, won the world of human life and preventing and treating illnesses open secrets "box" key.
Currently, DNA restructuring technology has many achievements. Recombinant DNA of the 20th century, to the largest technology applications in medicine, including active protein and vaccine peptide, the production, the disease occurrence mechanism, diagnosis and treatment of separation, new genes and environment monitoring and purification.
Many active peptides and proteins with treatment and prevention of diseases, they are from the corresponding gene. But due to the organization cells, so using yield a conventional methods to get enough for the clinical application.
Genetic engineering is a breakthrough in the limitations, to this kind of peptides and proteins, we have successfully produced in the treatment of diabetes and schizophrenia, leukemia and some insulin resistance of cancer therapeutic entity for treatment of disease, dwarf -- interferon human growth hormone therapy acromegaly and acute pancreatitis suppression of growth hormone release of product factor etc.
Genetic engineering can also will live on the DNA into the antigen such microbes by microorganisms, immunological stress in the host body growth can produce as weak, poison and stimulate doses of antigen long duration. Currently developing genetic engineering vaccine had dozens of many aspects, in dealing with leprosy coli bacteria are against e., pertussis, neisseria gonorrhoeae ShuangQiuJun etc, meningitis, In dealing with hepatitis a virus is for hepatitis b, cytomegalovirus,, herpes simplex, influenza, HIV vaccine... etc. China hepatitis b carriers and hepatitis b patients 1200 million, this situation as more Chinese scientists spurred by successfully developed hepatitis b vaccine made great social benefits and economic benefits.
Antibodies are the body's immune system is one of the main weapon disease resistance, founded in the 1970s monoclonal antibody technique in preventing disease-resistant aspects though plays an important role, but because it is difficult to achieve single RenYuan sex resistance, single resistance in the clinical application of limited. To solve this problem, in recent years, scientists using DNA restructuring technology has gained RenYuan sexual antibody, the antibody can guarantee the antigen and specificity and loyalty, and ensure the normal functions. Currently, there are many such antibodies in clinical trials, such as the resistance of single RenYuan special genetic marker, known as her2 breast cancer has entered the resistance test, Ⅲ period of single resistance RenYuan IGE Ⅱ has entered the period of treatment of asthma experiment.
Antibiotics in the treatment of the disease has played an important role in increasing Numbers, with antibiotics, with traditional methods and new antibiotic that chance. In order to obtain more new antibiotic, using DNA restructuring technology has become an important means of. People have won dozens of genetic engineering "heterozygous" for the clinical application of antibiotic, opening a new treatment.
As noted above mentioned gene engineering peptide, protein, vaccines, antibiotics, not only in drug prevention and control effectively avoid disease, but in some aspects in traditional method is also often similar drugs, thus producing more people.
Human diseases are directly or indirectly related with genes, at the genetic level on the diagnosis and treatment of disease, can achieve diagnostic accuracy of the etiology and primitivism, and can make the diagnosis and treatment of work to high sensitivity and specificity, convenient quickly. Gene level in diagnosis and treatment in professional called gene diagnosis and gene therapy. Currently genetic diagnosis as the fourth generation of clinical diagnosis technology has been widely applied to genetic diseases, cancer, cardiovascular and cerebrovascular diseases, virus disease and parasitic disease germs such diagnosis, And the object of gene therapy is through DNA restructuring specific functions of the technology to create a genetic recombination, to make up for lost, the function of genes, and to increase or a correction or abnormal cells.
In theory, gene therapy is ZhiBen cured without any adverse effects of therapy. However, although has more than 100 international gene therapy scheme is in clinical trials, but the gene therapy in theory and technology of some problems still make this treatment from the large scale application and a long distance. Whether the gene causes or implementation of genetic diagnosis, gene therapy, research mechanism, the disease is the key to understand the prerequisites for specific diseases related gene. With the human genome project ", "the scientists to human genes will get all the comprehensive understanding, which is formed by genetic restructuring to human health technology to create the conditions.
However, though genetic technology to human shows its fantastic "magic" as the charm, but also has a large number of scientists to this technology development and ecological ethic evolution to the human nature impact showed great concern. Theoretically, this technology is to make the development of a perfection of human have created any life forms or never had the ability of biology. People can imagine how this will be the result?
Scientists in DNA found outside the genetic code unless the new password
According to reports, the United States and Taiwan, they have Israeli scientists believe in DNA (to liu, except the genetic code) found outside the second password. New password for decision -- namely nuclear body of DNA protein surrounded by the position (--. The reel and protection and control of the way to DNA itself.
The findings could open, if that higher rates of relevant control mechanism of genetic information. For example, every kind of human cells to activate the genes needed, but can't touch other kinds of genes, used by cells is the key and mysterious process.
The institute of w) stuffed with America, northwestern university of Wisconsin meal and colleagues in the issue of "natural" scientific journals in writing, described the new password DNA.
Each individual cells are engaged in SanQianWanGe nuclear body. The nuclei are needed so much, because each line of DNA coated paper. Only a nuclear body, each DNA contains hundred units of a spiral of chromosomes, and a single DNA molecules in length may have as a unit 225 million.
Biologists have suspected for years, some of the DNA, especially those most easily bend DNA, may be more advantageous than other position of nuclear, but overall pattern is not obvious. Nowadays, dr wylton liger and analyzed approximately 200 position within the yeast gene sequence, these are both known nuclear body intertwined, they found a really exist hidden.
Through the understanding of this model, their successful predictions about five other organisms nucleation body position. This model is more easily bend can make DNA, and close the bag check two sequences. But in this mode, every body position of nuclear intertwine only several sequence, so it doesn't appear. Because of its formation conditions are loose and therefore does not conflict with the genetic code.
2008年11月10日星期一
人类遗传变异
五六万年前的这群人，为什么要离开位于非洲东部的家乡？确切原因至今仍是一个谜，可能因为气候发生变化，或者曾经丰富的贝壳类食物的数量突然锐减，才迫使他们向其他大陆迁移。不过有一点是肯定的：这批最早离开非洲的早期人类，已具有现代人的体质和行为特征——较大的脑容量和较强的语言交流能力。抵达亚洲大陆后（登陆点是今天的也门），现代人类的先祖们在此后上万年的时间里，继续向其他大陆进发，直至来到位于南美洲最南端的火地岛（Tierra del Fuego），才停下了脚步。
对人类的起源，科学家已从人类骨骼化石中有所了解，但祖先们遗留下来的实物太少，很难据此描绘出那段遥远历史的全景图。过去20 年间，人类遗传学家利用DNA 分析法，寻找早期人类迁移的证据，以填补古人类学的空白。
对所有人而言， 细胞内的DNA 有99.9％都是相同的，但就是这不同的0.1％，致使个体间的体质特征出现极大的差异。如果比较东非人与美洲土著人的DNA，科学家能从中得到人类世系，以及不同族群在各个大陆间迁徙的重要线索。遗传学家以前认为，只有父亲传递给儿子，或者母亲遗传给孩子的DNA，才具有化石般的研究价值，但最新研究改变了他们的看法，也让他们的关注点，从少部分DNA 片段扩大到整个人类基因组中的数万个核苷酸。
通过对人类基因组的研究，科学家提出了一些早期人类的迁移路径，其中一些在最近几个月才发表出来。这些研究进一步证实，现代人类起源于非洲。这也让人们认识到，遗传多样性是如何从非洲大陆发源，并扩散到世界其他地方的。如果把人类世系看作一棵“进化树”，“树根”就是非洲原著民桑人（San people），最新长出的“树枝”则是南美洲的印第安人和太平洋岛上的居民。
对人类遗传变异的研究，最早可以追溯到第一次世界大战。当时，两名在希腊塞萨洛尼基工作的医生发现，驻守该城士兵的血型为某种特定血型的概率，与他们的国籍有很大的关系。由于蛋白质差异可以反映相应基因的变化，因此，从上世纪50 年代开始，意大利人类遗传学家路易吉·卢卡·卡瓦利－斯福扎（Luigi Luca Cavalli-Sforza）通过检查血型蛋白来规范不同人群间的遗传差异研究。
1987 年，美国加利福尼亚大学伯克利分校的丽贝卡·L·卡恩（Rebecca L. Cann）和艾伦·C·威尔逊（Allan C. Wilson）基于线粒体DNA 的分析结果，发表了一篇震惊世界的论文：两位科学家在论文中指出，由于线粒体DNA 只会由母亲遗传给后代，他们经过研究发现，所有人的祖先都可追踪到一位生活在距今20 万年前的非洲女性身上。全球各大媒体争相报道这一重大发现，并声称现代人类的祖先就是那位“非洲夏娃”（这里说的“夏娃”并非《圣经》中的夏娃，她不是人类历史上的首位女性，而是指现有人类都是她的后代）。
对人类的起源，科学家已从人类骨骼化石中有所了解，但祖先们遗留下来的实物太少，很难据此描绘出那段遥远历史的全景图。过去20 年间，人类遗传学家利用DNA 分析法，寻找早期人类迁移的证据，以填补古人类学的空白。
对所有人而言， 细胞内的DNA 有99.9％都是相同的，但就是这不同的0.1％，致使个体间的体质特征出现极大的差异。如果比较东非人与美洲土著人的DNA，科学家能从中得到人类世系，以及不同族群在各个大陆间迁徙的重要线索。遗传学家以前认为，只有父亲传递给儿子，或者母亲遗传给孩子的DNA，才具有化石般的研究价值，但最新研究改变了他们的看法，也让他们的关注点，从少部分DNA 片段扩大到整个人类基因组中的数万个核苷酸。
通过对人类基因组的研究，科学家提出了一些早期人类的迁移路径，其中一些在最近几个月才发表出来。这些研究进一步证实，现代人类起源于非洲。这也让人们认识到，遗传多样性是如何从非洲大陆发源，并扩散到世界其他地方的。如果把人类世系看作一棵“进化树”，“树根”就是非洲原著民桑人（San people），最新长出的“树枝”则是南美洲的印第安人和太平洋岛上的居民。
对人类遗传变异的研究，最早可以追溯到第一次世界大战。当时，两名在希腊塞萨洛尼基工作的医生发现，驻守该城士兵的血型为某种特定血型的概率，与他们的国籍有很大的关系。由于蛋白质差异可以反映相应基因的变化，因此，从上世纪50 年代开始，意大利人类遗传学家路易吉·卢卡·卡瓦利－斯福扎（Luigi Luca Cavalli-Sforza）通过检查血型蛋白来规范不同人群间的遗传差异研究。
1987 年，美国加利福尼亚大学伯克利分校的丽贝卡·L·卡恩（Rebecca L. Cann）和艾伦·C·威尔逊（Allan C. Wilson）基于线粒体DNA 的分析结果，发表了一篇震惊世界的论文：两位科学家在论文中指出，由于线粒体DNA 只会由母亲遗传给后代，他们经过研究发现，所有人的祖先都可追踪到一位生活在距今20 万年前的非洲女性身上。全球各大媒体争相报道这一重大发现，并声称现代人类的祖先就是那位“非洲夏娃”（这里说的“夏娃”并非《圣经》中的夏娃，她不是人类历史上的首位女性，而是指现有人类都是她的后代）。
親子鑒定
親子鑒定的基本原理：人類基因組是一個結構十分穩定的體系，同時又是一個變異的體系。在長期的進化過程中，基因組DNA的序列不斷發生變異。這些變異有些被保存下來，導致了不同種族、群體和個體間基因組的差異和多態性，除同卵雙生子外，沒有兩個個體基因組是完全相同的。
親子鑒定是根據人類遺傳學的理論和實踐，從子代和親代的形態構造或生理機能方面的相似特點，分析遺傳特徵，對可疑的父與子或母與子之間的親生關係進行判斷，並作出肯定或否定的結論。法醫學的親子鑒定方法，有血型鑒定，外貌特徵的對比，皮膚紋理的檢查，遺傳疾病的檢查，耳垢的區別，味盲的檢查，以及受孕期、生產期，生殖能力的推斷等
DNA親子鑒定的原理和程序
DNA是從幾滴血, 腮細胞或培養的組織纖內提取而來。用疇素將DNA樣本切成小段, 放進喱膠內, 用電泳槽推動DNA小塊使之分離——最細的在最遠, 最大的最近。之後, 分離開的基因放在尼龍薄膜上, 使用特別的DNA探針去尋找基因, 相同的基因會凝聚於一, 然後,利用特別的染料,在X光的環境下,
便顯示由DNA探針凝聚於一的黑色條碼。小孩這種肉眼可見的條碼很特別，一半與母親的吻合,一半與父親的吻合。這過程重覆幾次,每一種探針用於尋找DNA的不同部位並影成獨特的條碼, 用幾組不同的探針, 可得到超過99.9%的父系或然率或分辨率。
親子鑒定是根據人類遺傳學的理論和實踐，從子代和親代的形態構造或生理機能方面的相似特點，分析遺傳特徵，對可疑的父與子或母與子之間的親生關係進行判斷，並作出肯定或否定的結論。法醫學的親子鑒定方法，有血型鑒定，外貌特徵的對比，皮膚紋理的檢查，遺傳疾病的檢查，耳垢的區別，味盲的檢查，以及受孕期、生產期，生殖能力的推斷等
DNA親子鑒定的原理和程序
DNA是從幾滴血, 腮細胞或培養的組織纖內提取而來。用疇素將DNA樣本切成小段, 放進喱膠內, 用電泳槽推動DNA小塊使之分離——最細的在最遠, 最大的最近。之後, 分離開的基因放在尼龍薄膜上, 使用特別的DNA探針去尋找基因, 相同的基因會凝聚於一, 然後,利用特別的染料,在X光的環境下,
便顯示由DNA探針凝聚於一的黑色條碼。小孩這種肉眼可見的條碼很特別，一半與母親的吻合,一半與父親的吻合。這過程重覆幾次,每一種探針用於尋找DNA的不同部位並影成獨特的條碼, 用幾組不同的探針, 可得到超過99.9%的父系或然率或分辨率。
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