Long time back when farmers tried new breed of seeds for crops. They found that the yield was pretty high than the earlier type of seeds. So what actually made them get such a high yield? Why new types of crops were immune against certain type of pests?
Ancient people noticed the improvement in plant crops and domesticating animals by selective breeding. Their knowledge was based on experience and was very incomplete. Various domestic animals like oxen, sheep, horses, cats, camel and different types of dogs in the period of 8000BC and 1000BC. They also followed selective breeding. Around 5000BC many different crop like wheat, rice and maize were cultivated. Our ancestors tried to manipulate genetic composition of crop varieties.
But, genetics came into existence as a set of scientific principles and analytical procedures by the experiments of an Augustinian monk ‘Gregor Mendel’ in 1866. He performed a set of experiments that proved the existence of biological factors which are responsible for the transmission of traits from generation to generation. Gregor mendel’s work was published in 1866 but was largely unknown until duplicate work was cited in 1900 by Carl Correns. Mendel’s work became recognised as explaining the transmission of traits in pea plants and all other higher organisms.
These biological factors are what we call ‘genes’ today. The study of genes gave rise to the discovery of chromosomes and also to the advance study in genetics. Further work revealed that chromosomes consist of DNA and protein, and subsequent studies allowed the conclusion that DNA is, in fact, the hereditary material. Deoxyribonucleic acid, DNA is a weakly acid substance present in the nucleus of a cell.
It was observed that the nuclei of male and female reproductive cells fuse during the fertilization process. This observation suggested that sperm and egg nucleus was responsible for the inheritance of traits. Next was the discovery of thread like substance inside the nucleus, which is called to be chromosomes. They can split during cell division. These characteristics of chromosomes ensure to produce each daughter cell with an identical complement of chromosomes.
It was evident by 1990 that, the number of chromosomes within the spices is constant, while it differs among the species. Also chromosomes are considered to be the carries of genes. Furthermore studies showed that DNA along with certain proteins, are present in chromosomes which are genetic materials. By the later investigations, it was widely accepted that DNA is the structural framework that hosts the proteins, which intern said to be the genetic material. However, it was considered that genes are DNA.
Heredity, the phenomenon of inheritance has been of interest to humans since long before the existence of actual principles and scientific researches.