The development of natural sciences at the beginning of the twentieth century led to the identification of the basic principles of heredity. At the same time, terms were introduced into circulation that describe the basic concepts of modern genetics. They were "gene" and "genome".
The term "gene" denotes a unit of hereditary information that is responsible for the formation of a certain property in a host organism. Gene transfer is at the heart of the entire reproduction process in nature. This term was first used by botanist Wilhelm Johansen in 1909.
Today it is known that genes are specific sections of DNA (deoxyribonucleic acid). Each gene is responsible for transmitting information about the structure of a protein or ribonucleic acid (RNA), which, among other things, is involved in the process of cell synthesis.
Usually, a gene contains more than one piece of DNA. The structures directly responsible for the transmission of hereditary information are called coding sequences. However, there are structures in DNA that influence gene expression. Such fragments are called regulatory. In other words, genes consist of coding and regulatory sequences, which are located separately in DNA.
The term "genome" was coined by Hans Winkler in 1920. Initially, it designated a set of genes for a single unpaired set of chromosomes inherent in a biological species. It was believed that the genome fully covers all the properties of organisms of a particular species. However, further research showed that this is not entirely true, so the meaning of the term has changed somewhat.
It was found that in the DNA of most organisms there are many "junk" sequences that do not encode anything. In addition, some of the genetic information is contained in DNA located outside the cell nucleus (outside the chromosomes). And also some of the genes encoding the same trait may differ in structure. Thus, the term “genome” today is understood as a certain collective set of genes contained both in chromosomes and outside them. It characterizes the properties of a certain population of individuals, however, the genetic set of a particular organism can differ significantly from its genome.