Difference between Genes and Genomes
Every species has a unique set of information stored in its DNA as inherited characteristics. These characteristics are encoded in the DNA molecules in the language of chemistry. While learning about DNA we come across terms such as Genes, Genomes, DNA sequences etc. Let's understand more about them:
1. Genes:
Genes are the specific inherited information passed from the parents to offsprings. Gregor Mendel was the first to suggest the existence and transmitting process of Genes. He considered Genes to be the "factors" that are shared between two generations, however at his time DNA, the genetic messenger, was not discovered. Later after the discovery of the DNA it clarified that Genes are the specific segments or portions of DNA. These segments have the power to control specific heredity characteristics. The study of Genes is called Genetics.
Every cell in our body contains the exact same DNA. Your eyes cells, nose cells stomach cells, etc all have the complete and same DNA found in each and every part of your body but these are behaving differently to create eyes, nose, stomach etc. This is because even though all the cells have the same DNA, still only specific Genes or segments of the DNA are active in different cells through a process known as Gene Expressions. Due to this characteristic different cells grow differently even though they all contain the same DNA.
2. Genomes:
A Genome of an organism is its whole hereditary information and is encoded in DNA. This is almost true for all organisms except some viruses which do not contain DNA and have RNA as the basic information carrier. So basically, an organism will contain only one genome but thousands and millions of Genes.
The study of genome properties of related organisms is called genomics. Evolution of genome can be identified with the help of genome composition, which includes genome size and proportions of non-repetitive and repetitive DNA. If we consider the human genome, it contains 23 chromosomes. Out of 23, only one chromosome is a sex determinative while the remaining 22 chromosomes are autosomal chromosomes. There are approximately 20,000 to 25,000 genes of the human genome. To identify and map the sequence of chemical base pairs which make up the human DNA, there an international project was started in 1990 called ‘The Human Genome Project’ which concluded in 2003.
