All World
Gayatri Pariwar

The dominant influences in the formation of human personality are generally believed to be environment and enterprise. But this belief holds true only to a certain extent. It is a matter of common observation that children born and brought up in similar circumstances develop major mental and emotional differences later. This is primarily on account of the basic life-elements, which go to make the person of an offspring.

These subtle influences come down over many previous generations from both paternal and maternal sides. They combine to maintain the continuity of hereditary characteristics and also mutate in a strange way to spawn entirely new traits and identities, thereby taking evolution forward.

Scientists have been able to uncover the fundamental basis of life of not only human beings but of all the life forms belonging to animal and plant worlds. Since the second half of the 20th century, a great amount of research has been made in this direction and almost daily new findings are published. This rapid and profuse work is propelled by advances in electron microscopy and cybernetics in which information from different fields are collated and integrated into a composite whole.

All living organisms from the simplest amoeba to the most complex human body have been formed by the same life-chemical, the DNA or deoxyribonucleic acid. The DNA contains in chemically coded form - the blueprint of life, i.e., all the information needed to build, control and maintain a living organism. The DNA has extremely tiny spring-like structures, which can be seen through an electron microscope. The defined stretch of DNA is called genes. The genes have memory banks and they continually feed the body cells with instructions about the formation and functioning of body organs. This way co-ordination among the billions of body cells is achieved.
DNA is found in every living organism except in human RBC and certain types of viruses. An adult human body has 600 billion “energy packets” of DNA. In shape and chemical composition, all of these are similar whether in humans or animals or even in grass blades. The key to all of life’s diversity is hidden in DNA. The particular order of its constituent bases determines whether an organism is a human or a bird, fish, insect or vegetable. An Indian-American scientist Dr. Hargovind Khurana made path-breaking discoveries about the structure of RNA (ribonucleic acid) and was awarded the Nobel Prize in 1968.

According to scientists, DNA controls and balances biochemical parameters and BMR (Basic Metabolic Rate). Sitting in the nucleus of the cell it keeps on issuing signals and commands about the pre-ordained physical, functional and behavioral traits. All of body’s organs - heart, lungs, kidneys, intestines, skin, eyes, ears, nose etc. take shape in accordance with these directions. Different functions like digestion; heart beating and even thoughts and emotions depend on these signals. This process starts in the embryo and goes on till death.

The structure of DNA molecule was first unravelled by Dr. James Watson and Dr. Francis Crick in 1953. It is made up of a double helix of two chains coiled around each other like a spiral tape. Arranged lengthwise, this tape will measure about five feet. The number of cells in a young person may reach up to 600 billion. The combined length of the DNA molecules of all the cells will form a tape long enough to measure the whole universe. A cell biologist of Chicago University, Dr. George Beedal, explains that the DNA molecule is so lengthy because it has to encapsulate coded information about an entire life span. The DNA molecule consists of three main chemical substances- sugar, phosphate and nitrogen compounds. Each of the two chains is made up of alternating pentose sugar (deoxyribose) and phosphate groups with nitrogen compounds linking the two strands like the rungs of a twisted ladder. Scientists believe that all the mysteries of life are hidden in these nitrogen compounds and to understand their mysterious signals massive research efforts are going on.

In the beginning of the 20th century, an American scientist Dr. Sutton told the world about chromosomes. These are thread-like bodies existing in pairs inside the nucleus of every cell of a living organism. Chromosome number is characteristic of a species. Humans have 46 chromosomes; half of which come from the father and half from the mother. Out of these 23 pairs, 22 are matched pairs, called autosomes. The 23rd pair is sex chromosome. This pair determines the sex of a baby. In male, the pair is ‘XY’ and in female, it is ‘XX’. Every cell of our body has the same number of chromosomes except the reproductive cells (gamets; egg or sperm), which have exactly half the number. A new life is formed by the fusion of two gamets. Chromosome is made up of 50-60% protein, 25-48% DNA and the rest of RNA. Each chromosome has one very large strand of DNA, which is coiled and folded to produce a compact body. Tiny particles of nucleo-protein, called genes, exist in the chromosome in the manner of knots tied at regular intervals on a length of thread.

Genes are the basis of physical and functional units of heredity. They first reach the zygote, which is formed as a result of male and female gamet union. From there, through cell division, they spread to every cell and control basic cellular operations. According to scientists every gene is located at a specific place in the DNA which is called ‘locus’ and the sequence of these locations is extremely important as it determines all of an organism’s characteristics. From its location, the gene transmits genetic information to the RNA molecule.  RNA, in turn, goes to the cell cytoplasm and synthesizes proteins so that different agencies and chemicals concerned with body formation may be accurately instructed about their duties and functions.

Genes are responsible for preservation and continuity of hereditary traits. Heredity means transmission of physical and mental-emotional characteristics- visible or invisible – from one generation to another. This generational continuum constitutes the basis of the evolutionary progress of life. Although offspring exhibits visible likeness to their parents, they are also different in many ways. These differences called “variance” in scientific terms may exist between two children of the same parentage, or among different members of the same family, or among different animals of the same species. The science, which studies the underlying factors behind such similarities and dissimilarities, as also the behavioral traits and physical features of the offspring and the mechanism of their transmission from parents to the next generation is called “genetics”. Genetics, however, is not concerned with those changes that occur on account of environment, nurturing, experience and training.

Genetics, or the science of heredity is a branch of biology. Its sub-branch is “eugenics” which deals with race improvement. This science is under serious scrutiny as a new tool of great promise in the progress of human evolution and civilization.
The ancestors of modern man were comparatively superior in terms of physical and intellectual abilities as well as longevity. Serious efforts are underway to make up this shortfall in modern man and raise him to his ancestors’ measure. Through genetic engineering and manipulation of DNA, harmful and disease causing genes are sought to be replaced by beneficial genes. The ongoing researches in this direction hold the promise that some day desired changes would be carried out in the structure of this most subtle and ubiquitous basic element of life and such human beings could be produced who are more strong, more talented and more long-living than their ancestors. Dr. Watson and Dr. Crick had this unbounded potentiality in mind when on the occasion of receiving the Nobel Prize in 1962 they said, “The key is in hand, but not the operator. Hopefully, we would find that too some day. Then man who is today a puppet in the hands of nature would make the latter dance to his tunes.”