The Role of DNA in the Process of Heredity
The most reliable evidence of evolution is not located in the earth fossils, but in all people and other organisms. When investigating human bodies and the bodies of other representatives of the fauna, the researchers deal with the facts that cannot be explained without the implementation of evolutionary theory. Some of such phenomenon are the DNA molecules and the genetic code they contain. The paper investigates the genetic inheritance and the functions of DNA.
DNA is the basis for the understanding of the evolutionary processes and life. It is one of the clearest evidence of the development of all vivid organisms on the Earth. All the organisms on the planet have certain common features. They all consist of cell and use ATP as the source of energy. They also use a certain number of amino acids as the construction material, etc. However, one of the most important elements of the similarity consists in the fact that that the basis of any organism lies the genetic code contained in the DNA molecule in each cell of the organism. The mechanisms for the reading of this code and reproduction of the proteins with the RNA are also similar.
One of the most interesting facts is that in the process of this code (the sequence of amino acids) of one organism and the comparison of the code with the other one, it is possible to discover the degree of relationship between the organisms. With the help of genetic sequences, is is possible to create the relationship scheme.
There, we will be able to see that the mutual ancestor of Homo Sapiens and Chimpanzee is also related to the other Hominoidea. However, at the different stages of evolution, there took place different mutation. It is like a family tree, where all the species on the Earth are brothers and sisters. However, the scale of the picture is completely different.
Weintraub states that after the discovery of DNA, scientists do not have any doubts that the evolution is the fact. After the publication of the works by Darwin, there existed some doubts about his theory, and the discovery of the storage of inherited information put the end to the numerous argues among the biologists. However, the situation could be completely different, if, for example, the scientists could discover that not all the organisms are based on the DNA. In this situation, the theory of evolution would fail. The discovery of DNA molecule is one of the most powerful evidence that is impossible to be ignored. It is one of the main discoveries in the biological studies.
Heredity and changeability are the main qualities of any vivid structure. The article “History of Biology: Inheritance” states that the knowledge about the qualities and the organization of nature is constantly deepened and expanded. In 1860th, Mendel provided the first ideas about the organization of the inherited material. Based on his experiments on peas, the scientist stated that the inherited material is discrete. It is represented by separate abilities to inheritance, which are responsible for the development of certain features of the organisms. Mendel stated that in the inherited material of the organisms that develop with the help of sexual reproduction, a couple of the allele variants provides the development of a certain quality. These alleles are provided by the sex cells of both parents. In the process of gametes creation, each of them receives only one of the allele deposits. In 1909, Johannsen named these “allele deposits” as genes.
According to the article “History of Biology: Inheritance”, 1880th were characterized by the important discoveries in the field of cytology. There were described the processes of mitosis of meiosis that are the division of somatic and sex cells in the process of which the nuclear structures (chromosomes) are divided between the daughter cells. The data about the type of the chromosome distribution in the proves of cell division allowed to carry out the discovery that the heredity of the qualities in a chain of generations of cells and organisms is determined by the inheritance of the chromosomes. The chromosomes now are considered to be the material sources of the heredity code.
The further investigation of the chromosome theory of heredity that united the ideas about genes and chromosomes took place at the beginning of the XX century by Morgan. The experiments carried out on drosophila showed the correctness of the ideas about the role of chromosomes in the provision of heredity. The scientist discovered that the genes are placed in chromosomes in the linear order. The genes of each chromosome create groups, the number of which is determined by the number of chromosomes in sex cells. The genes of one group, as a rule, are inherited together. However, in a number of cases, there takes place their recombination together with the crossing over, the frequency of which depends on the distance between genes. Thus, the chromosome theory reflects one of the most important principles of genetics that is the unification of discreetness and the endlessness of the inherited material.
The life diversity on the planet is provided by the diversity of protein molecules that carry out different biological functions. The structure of proteins is determined by the set and the order of location of amino acids, in their peptide chains. This sequence of amino acids in the peptides if coded in the DNA molecules with the help of genetic code. The relative primitivism of the DNA structure that is the sequence of only four different nucleotides did not allow the investigators to consider this connection as the material for heredity and changeability that codes diverse information.
One of the main qualities of hereditable material is the ability of the replication. This quality is provided by the peculiarities of the chemical organization of DNA molecule that consists of two complementary chains. In the process of replication, each polynucleotide chain of the mother molecule produces a complementary chain. As the result, one double spiral of DNA produces two identical double spirals. This way of molecule reproduction is called half-conservative.
It is impossible to count the number of processes that take place in an organism within a second. These processes are so complex that they require the involvement or “regulators: that control the system, determine the order of development and accelerate the events. These regulators are named enzymes. Each of the enzymes carries out a specific function. For example, some of them enable the process of DNA replication, the others are involved in the process of nutrition elements fermentation. They also support the normal rhythm of the vital activity of a certain organism. One of the primary tasks of enzymes is the stimulation, inhibition, and acceleration of different chemical reactions. For example, the enzyme that takes carbon dioxide from the blood, allows the organism to support the process of breathing.
The existence of DNA is the most important discoveries in the history of the biological studies. It approved that Darwin`s theory of evolution was right because all cells of the organisms that exist on the Earth are based on DNA. DNA plays an important role in the process of genetic inheritance. The DNA mollecules transfer the genetic information from the mother cell. Enzymes support the work of DNA, for example, they support DNA replication, and, at the same time, they are able to carry the other functions, for example, to take carbon dioxide out of the blood.