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Reading Guide 1: DNA Codes are the Only Carriers of Human Genetic Information
(Reading Guides 1 and 2 are written to help the readers understand the core contents of this website. We recommend that the readers read the Guides twice, once before and once after reading all chapters.)
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Modern life science discovered that DNA coding in human cells are the only carriers which store the genetic information of life.
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The code, DNA, has become a very familiar but yet mysterious term. Though existing in our bodies, DNA is still an abstract concept for many people. What does it look like? How can we see it? Why does it carry the genetic information of life? How is it linked to the origin of human beings? Most people cannot answer many of these questions. It is hoped that the following content plus material in the part 2 of this website will help you gain an initial understanding of DNA as well as how scientists can see the origin of human beings by studying it.
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I: Discovery of the genetic information of life
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1. History of the discovery of the genetic information of life
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For a long time, human beings had known that the information of life comes from our parents through heredity. However, without a microscope of 200× or higher magnification, they cannot see sperm, the only carrier of life information from the father.
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In 1677, Antonie van Leeuwenhoek, the Dutch microscope maker, discovered sperm for the first time using a 300x microscope he developed. As a result of this discovery, we know that the contribution of a father is not just the semen but also numerous tadpole-like sperms in the semen. Thus, the history of our understanding of the carrier of paternal genetic information was created. With increasing magnification of future microscopes, only one sperm was needed to combine with an egg from the mother, under normal conditions, to create a new life.
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With a high-powered microscope, it was identified in 1950s that the nucleus of a human cell contains 23 pairs (or 46) of chromosomes, 23 from the father and 23 from the mother. Moreover, the discovery of mitochondrial DNA in the eggs has further advanced our understanding that the chromosomes and mitochondria exclusively carry the genetic information of life.
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To fully understand the true nature of genetic information, we rely on high-powered microscopes and X-ray diffraction photography. These instruments show that DNA is a molecule with a double helix structure. This long DNA molecule shaped like a spiral staircase can be simplified into a DNA coding sequence expressed by four nucleotide base characters, i.e. Adenine (A), Thymine (T), Cytosine (C) and Guanine (G). The genetic information in mitochondria is a ring-shaped DNA coding sequence expressed by 16,569 DNA base characters (A, T, C, G). (See the part 2 of this website)
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Conclusion: The DNA coding sequence in the 46 chromosomes and ring-shaped DNA coding sequence in mitochondria carry all the genetic information of life. There exists only one thousandth difference in the DNA coding sequence between any two people in the world.
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2. Conveyance of the genetic information of life
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New life starts with the process of fertilization of an egg. Among the billions of sperms, only about 1000 reach the vicinity of the egg. In the end, only one sperm finally enters the egg.
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Every sperm of a man contains 22 autosomes and one sex chromosome (i.e. Y chromosome or X chromosome). If the sperm contains a Y chromosome, the fertilized egg will be an embryo of a male; if the sperm contains an X chromosome, the fertilized egg will be an embryo of a female. These two kinds of sperm account for one half of the total respectively. The Y chromosome comes from the father of the man, and the X chromosome from the mother of the man. The autosomes in the sperm come from both the father and mother of the man, formed by synapsis of meiosis (see Part 6 -- The key of DNA decoding: Formula P).
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The autosomes on synapsis contain the genetic information from both the future grandfather and grandmother of the embryo. Every spermatogonium will produce four different sperm through synapsis, while many spermatogonia will produce many sperms through their own synapsis, which everyone is unique. However, the difference in DNA codes between them is less than one thousandth.
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Each sperm cell is shaped like a tiny tadpole. The head of each “tadpole” contains the DNA coding sequence of the 23 chromosomes with a total set of about 3 billion of DNA characters. Such orderly coding sequence carries all paternal genetic information to include both the physical and non-physical genetic information. The head of the “tadpole” is small with the length, width, and height of around 3 micrometers, and yet it contains 3 billion DNA codes and other material of DNA encoding. Such storage density would be hard to achieve even by the immense storage capacity of the modern computer! (See section1 of Part 9).
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Likewise, an egg also contains 23 chromosomes with the sex chromosome being X only. Similar to the formation of sperm, by synapsis of meiosis of eggs, the chromosomes contain the genetic information of the future maternal grandfather and maternal grandmother of the embryo. The embryo formed by fertilization of the egg with a sperm now acquires the complete maternal and paternal genetic information.
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II: Two kinds of genetic information of life
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The genetic information of life has two parts, i.e. the physical genetic information and the non-physical genetic information (or the intangible genetic information）.
1. Physical genetic information in the chromosomes
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The most genetic information in DNA exists in the chromosomes. Every chromosome contains one DNA molecule, which can be deemed as a long string of DNA coding sequence. The longest human chromosome is the No. 1 autosome, which is composed of 249,250,621 DNA codes. The Y chromosome is composed of 59,373,566 DNA codes. (See Part 7).
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The information contained in the DNA codes is expressed by the nucleobase weaving order on every chromosome’s DNA coding sequence. Since this concept is difficult for most people to understand, we might as well explain it by using a movie on a DVD as an example. For a DVD disc to contain the entirety of a movie, the information on it is completely composed of binary codes 0 and 1. Billions of characters composed of 0 and 1 are weaved together according to certain sequences in order to store the sound and action in the movie. Similarly, the four nucleotide codes, A, T, C and G, will weave together all unique features of the human body according to a specific sequence. For example, some sections define skin color, and others the height of our nose.
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The chromosome coding sequences of the scientific Adam and scientific Eve from 200,000 years ago have been strictly replicated over ten thousand of generations. The difference in DNA codes between them and us is only one half thousandth. Therefore, the difference in DNA codes should be one thousandth between their offspring in Africa and their offspring in Europe and Asia (See section 3 of CHAPTER II Who is the Husband of Mitochondrion Eve?).
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In 2006, the U. S. National Human Genome Research Institute (NHGRI) reported, “When researchers completed the final analysis of the Human Genome Project in April 2003, they confirmed that the 3 billion base pairs of genetic letters in humans were 99.9 percent identical in every person. It also meant that individuals are, on average, 0.1 percent different genetically from every other person on the planet.”
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For this very reason, one can explain the similarity in the physical appearance and physiology of all peoples in the world, the donation of blood, intermarriage, and the reproduction of offspring.
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The DNA coding sequences of chromosomes contain both gene-related and non gene-related sequences. All these sequences contain the “physical genetic information” of life. When the first fertilized egg comes into being, a new life is born. According to the existing knowledge, the over 30,000 genes in a cell determine the physiology, physique, and outer appearance of a person. However, the effects of the non-gene-related sequences cannot be determined yet.
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In the cell nucleus of a fertilized egg, the 23 chromosomes from the father and 23 chromosomes from the mother coexist without interchange. The DNA of the chromosomes is the same in the millions of cell nuclei replicated later in all parts of the body. Synapsis does not occur with the paternal and maternal chromosomes until sperm and eggs are formed leading to merge their genetic information, which is then passed onto later generations.
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The fertilized egg goes through mitosis, in which one cell divides to become two, two to four, four to eight and so on. In the beginning, the cells are replicated exactly alike. Of interest is the fact that at the stage of “cell differentiation” the DNA of nuclei remains the same, while the cytoplasm varies dramatically to form specialized cells for different parts of human body.
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Figure 1 46 Chromosomes in the Cell Nucleus
Figure 1 shows the disorderly dispersion of the perspective 23 chromosomes from the father and mother. However, they are like two teams managing cell growth. Each team has 23 commanders who orderly and jointly command the division and proliferation to transform a single embryonic cell into a grown-up adult. In addition, the 23 pairs of chromosomes will also be replicated to 40-60 trillion cells in the body. Persons with different body weights have different number of cells.
The DNA codes in the chromosomes may have special effects on cell growth through expression of coding information during the growth of the human body. Protein synthesis requires two steps: transcription and translation. DNA is transcripted to RNA (Ribonucleic acid), and then RNA is translated to proteins. The information of DNA codes will instruct the synthesis of all specific proteins to form different parts of the human body. His (or her) new identity is the result of both paternal and maternal physical genetic information. Meanwhile, human beings also possess the non-physical genetic information from both parents to make him/her an intelligent individual.
Let’s take a look at DNA segment of a single gene to help you understand what DNA codes are: 729 DNA coding sequences of the ZFY gene of a man’s Y chromosome (See Appendix: DNA Code Material of Gene Bank).
Human Y-linked zinc finger protein (ZFY) gene sequence
VERSION U24118.1 PRI 06-APR-1996
--1 gtgagttcca caggggtgtt atgatggagt tttagctagt aggccacatg tatttttatg
-61 tgttgaattt gaaagaaaaa atttcaaaat tcagtgatat tcatgaatgg ttttcttgga
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721 ctttcttag
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Molecular anthropology is based on these DNA codes to track the origin, proliferation, and migration of human beings. However, the research scope of this discipline does not cover the significance of pathology in DNA coding.
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2. “The non-physical genetic information” of the chromosomes
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Each child inherits not only a physical body but also the non-physical genetic information (or “intangible genetic information”) from his or her parents. No matter how you teach or train a chimpanzee, it will never be able to listen, talk, read, and write like an elementary school student and acquire an elementary school graduation diploma.
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So far, little research has been conducted about the non-physical genetic information. However, we should recognize that we have inherited from our parents some invisible ability. Such information does not include specific knowledge but the ability to learn knowledge. A child can naturally understand languages of his or her mother, learn to speak, read, and write and demonstrate skills in arts, sports, or other’s skill sets inherited from his or her parents. All these must be attributed to the inheritance of the non-physical genetic information from the parents.
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Since DNA codes in human cells are the only carriers storing human genetic information, the non-physical genetic information must also be carried by these DNA codes. Perhaps for a long time, we could not identify in the DNA codes which part of them carry such information, but unmistakably they exist in our codes.
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Therefore, by comparing the differences in DNA codes, we can identify the differences of humans’ non-physical genetic information. Dr. John Craig Venter, the Chief Scientist of the U.S. Genome Research, said: race is only a “social concept, not a scientific one.”
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The difference of “the non-physical genetic information” is only one thousandth or even one part per ten thousand among different races. The ability of human beings to listen, speak, read, write, and express emotions is similar despite racial differences. If properly trained, children from all remote places can become excellent college students.
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Figure 2 Determine the Sequence of DNA codes
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Human DNA samples can be collected from blood, oral mucosa, hair, body fluids, and other biological materials. After cell lysis, DNA separation, extraction, purification, and other steps, high quality DNA samples can be obtained. By a molecular bioengineering technique, the DNA sample is cut into many small DNA coding segments. Then, fluorescent labels are added and then put into an electrophoretic buffer solution. Then, this DNA sample is put into a sequencer and undergoes capillary electrophoresis separation. By exposing them to a laser and grating spectrum, DNA base information and small-segment DNA coding sequences can be determined. The combination of the smaller segments with lap joints of DNA codes at the ends form the larger segments of DNA coding sequences. As a result, the secret codes of our bodies appear before our eyes. They can be used to test the paternity and track the origin, heredity, and migration of human beings.
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III: What can we see from DNA codes?
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1. The American GenBank
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The American GenBank is an open sequence database that collects, examines and annotates all publicly available nucleotide sequences as well as the Amino acids they translated. It is managed by the National Center for Biotechnology Information (NCBI), a subordinate institution of the National Institutes of Health (NIH), in the United States.
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This database was established over thirty years ago and has become the most important, as well as influential, database covering the entire scope of biology. Millions of researchers across the world access and make use of this database free of charge.
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GenBank has collected DNA and RNA samples of over 100,000 biological species from laboratories all over the world. Its database increases exponentially and doubles every 18 months. As of the version published in February 2013, the database contained 162 million sequences and 150 billion nucleotide bases (i.e. DNA and RNA codes). This database is the result of research of not only of ten thousands of scientists, but it also involved the expenditure of billions of research dollars which provided the solid foundation of modern biology and molecular anthropology.
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All the DNA codes cited in this book come from the above database. The readers can check and compare information of all DNA codes at the GenBank website.
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2. Different scientific disciplines pay different attention to the DNA codes
Modern scientific disciplines closely linked to the DNA codes include Molecular Biology, Molecular Medicine, and Molecular Anthropology.
A key area of molecular biology concerns understanding how various cellular systems interact in terms of the way DNA, RNA, and protein synthesis function. On the other hand, molecular medicine is a scientific discipline which applies the theories and technologies in molecular biology in our understanding, research, and diagnosis of diseases. The two disciplines focus on DNA codes that constitute the genes. A total of over 30,000 genetic DNA codes have been identified so far which account for only about 3% of the total 3.1 billion DNA codes in the human genome.
Molecular anthropology, a branch of anthropology, analyzes the origin of human beings - the reproduction and migration of different nationalities by using the DNA genetic marker information in the human genome. It is a cross-fertilization of two scientific disciplines: DNA genetic marker analysis and anthropology. Its research methodology is to compare DNA sequences and identify the original sequence markers contained in these DNA sequences as well as the unique mutant DNA markers of different races. Based on the succeeding relationships from these sequences and markers, we can find the origin of man, evaluate kinship from different races, and identify where they came from and their migration routes. Molecular anthropology focuses on all 3.1 billion DNA codes of the human genome.
Mitochondrial disease and the mutation markers：
Human mitochondrial DNA codes are a ring-shaped sequence with 16569 base-DNA codes, including codes for 37 genes. The mitochondrial DNA coding sequences among all the people on earth are highly consistent. Due to DNA mutations in the process of human reproduction, mitochondrial DNA codes from different races vary by just about 1%. In 1981, the medical experts from the University of Cambridge sequenced the mitochondrial genome of one individual of European descent, i.e. Cambridge Reference Sequence (CRS), which remains as a major medical reference for all countries in the world (see Part II).
Medical research has proven that mitochondrial DNA mutation may lead to certain diseases and that the mother can pass such diseases to the next generation. So far, the scientists have identified some diseases caused by mitochondrial DNA mutation at some specific positions. For example, T to G at position 8993 (T8993G) may change the property of the genes at the position and lead to retinal pigment degeneration. In addition, G11778A mutation may lead to hereditary optic neuro retinopathy, A3243G mutation to mitochondrial brain disease, T7445G to hearing loss, etc. These are all within the realm of molecular medicine.
Different from molecular medicine, the first concern of molecular anthropology is to ascertain why human mitochondrial DNA coding sequences are so consistent, and why both nucleotide base-DNA characters and position of the codes are the same at least across 16,400 positions. The only reason is that all human beings in the world come from the same mother. Mitochondrial DNA is inherited from the maternal side which gives birth to the Mitochondrial Eve Theory.
Afterwards, scientists wanted to find out the differences in mitochondrial DNA in different race groups inside and outside of Africa. It was founded that the non-African races have mitochondrial DNA mutation at three positions, i.e. A769G (A change to G at Position 769), A1018G and C16311T. This is the well-known “L3 Mitochondrial DNA Marker” in molecular anthropology, which shows that all non-African races are the offspring of the same woman. At the three positions, non-Africans’ DNA nucleotide bases are G, G and T. In contrast, most Africans have A, A, and C at these three positions .
The Theory of Evolution is unable to explain and unwilling to accept the conclusion of DNA code analysis that all human beings in the world are offspring of the same woman, and all non-African people are also the offspring of one woman.
Finally, what we need to think about is this: why are the gene and non-gene DNA coding sequences not different in the autosomes between men and women? The question will be answered from the perspective of codes and mathematics in next Part-Reading Guide 2.
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