In biology, a gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.


During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic trait. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gene–environment interactions. Some genetic traits are instantly visible, such as eye color or the number of limbs, and some are not, such as blood type, the risk for specific diseases, or the thousands of basic biochemical processes that constitute life.

Genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotypical traits. Usage of the term "having a gene" (e.g., "good genes," "hair colour gene") typically refers to containing a different allele of the same, shared gene.[1] Genes evolve due to natural selection / survival of the fittest and genetic drift of the alleles.

The concept of gene continues to be refined as new phenomena are discovered.[2] For example, regulatory regions of a gene can be far removed from its coding regions, and coding regions can be split into several exons. Some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs. Therefore, a broad, modern working definition of a gene is any discrete locus of heritable, genomic sequence which affect an organism's traits by being expressed as a functional product or by regulation of gene expression.[3][4]

The term gene was introduced by Danish botanist, plant physiologist and geneticist Wilhelm Johannsen in 1909.[5] It is inspired by the ancient Greek: γόνος, gonos, that means offspring and procreation.



The existence of discrete inheritable units was first suggested by Gregor Mendel (1822–1884).[6] From 1857 to 1864, in Brno, Austrian Empire (today's Czech Republic), he studied inheritance patterns in 8000 common edible pea plants, tracking distinct traits from parent to offspring. He described these mathematically as 2n combinations where n is the number of differing characteristics in the original peas. Although he did not use the term gene, he explained his results in terms of discrete inherited units that give rise to observable physical characteristics. This description prefigured Wilhelm Johannsen's distinction between genotype (the genetic material of an organism) and phenotype (the observable traits of that organism). Mendel was also the first to demonstrate independent assortment, the distinction between dominant and recessive traits, the distinction between a heterozygote and homozygote, and the phenomenon of discontinuous inheritance.

Prior to Mendel's work, the dominant theory of heredity was one of blending inheritance, which suggested that each parent contributed fluids to the fertilisation process and that the traits of the parents blended and mixed to produce the offspring. Charles Darwin developed a theory of inheritance he termed pangenesis, from Greek pan ("all, whole") and genesis ("birth") / genos ("origin").[7][8] Darwin used the term gemmule to describe hypothetical particles that would mix during reproduction.

Mendel's work went largely unnoticed after its first publication in 1866, but was rediscovered in the late 19th century by Hugo de Vries, Carl Correns, and Erich von Tschermak, who (claimed to have) reached similar conclusions in their own research.[9] Specifically, in 1889, Hugo de Vries published his book Intracellular Pangenesis,[10] in which he postulated that different characters have individual hereditary carriers and that inheritance of specific traits in organisms comes in particles. De Vries called these units "pangenes" (Pangens in German), after Darwin's 1868 pangenesis theory.

Sixteen years later, in 1905, Wilhelm Johannsen introduced the term 'gene'[5] and William Bateson that of 'genetics'[11] while Eduard Strasburger, amongst others, still used the term 'pangene' for the fundamental physical and functional unit of heredity

Gene: An Introduction

A gene is a fundamental unit of heredity that carries information for the production of a specific protein or functional RNA molecule. Genes are found in the DNA (deoxyribonucleic acid) of an organism and play a crucial role in determining its traits and characteristics. They provide the instructions necessary for the synthesis of proteins, which are essential for the structure and function of cells.

Key Points:
- Genes are units of heredity responsible for the transmission of traits from one generation to another.
- They are located on chromosomes, which are thread-like structures found in the nucleus of cells.
- Genes are composed of DNA, a long polymer made up of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
- The sequence of these nucleotides within a gene determines the order of amino acids in a protein, which ultimately determines its structure and function.
- Genes can be either coding or non-coding. Coding genes contain the instructions for protein synthesis, while non-coding genes have regulatory functions, controlling the expression of other genes.
- Mutations, or changes in the DNA sequence of a gene, can alter its function and lead to genetic disorders or variations in traits.
- Genes are inherited from parents and are passed on through reproductive cells such as sperm and eggs.
- The study of genes and their functions is known as genetics, which encompasses various branches such as molecular genetics, population genetics, and genomics.

Importance and Applications of Genes:
- Understanding genes and their functions is essential for advancing our knowledge of biology and medicine.
- Genes are involved in various biological processes, including growth, development, metabolism, and response to environmental stimuli.
- Genetic research has led to the identification of disease-causing genes, enabling the development of diagnostic tests and targeted therapies.
- Genetic engineering techniques allow scientists to manipulate genes, leading to advancements in agriculture, medicine, and biotechnology.
- Genes play a vital role in evolutionary processes, driving genetic variation and adaptation in populations over time.
- The Human Genome Project, a landmark scientific endeavor, aimed to sequence and map all the genes present in the human genome, providing invaluable information for medical research and personalized medicine.

In conclusion, genes are fundamental units of heredity that carry the instructions for protein synthesis and play a crucial role in determining an organism's traits and characteristics. They are composed of DNA and are inherited from parents. Understanding genes and their functions has significant implications for various fields, including medicine, agriculture, and evolutionary biology.