Gene

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.

Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species.

During gene expression, the DNA is first copied into RNA. 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.

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product.

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. Some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs.

Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes.

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.

Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific three-dimensional structure that determines its activity.

Most biological traits are under the influence of polygenes (many different genes) as well as gene–environment interactions.

A norm of reaction is a graph that shows the relationship between genes and environmental factors when phenotypic differences are continuous.

Genes evolve due to natural selection / survival of the fittest and genetic drift of the alleles.

These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction.

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.

Some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs.

The genome includes both the genes (the coding regions) and the noncoding DNA, as well as mitochondrial DNA and chloroplast DNA.

Most biological traits are under the influence of polygenes (many different genes) as well as gene–environment interactions.

A "polygene” or "multiple gene inheritance" is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait. The term "monozygous" is usually used to refer to a hypothetical gene as it is often difficult to characterise the effect of an individual gene from the effects of other genes and the environment on a particular phenotype. Advances in statistical methodology and high throughput sequencing are, however, allowing researchers to locate candidate genes for the trait. In the case that such a gene is identified, it is referred to as a quantitative trait locus (QTL). These genes are generally pleiotropic as well. The genes that contribute to type 2 diabetes are thought to be mostly polygenes. In July 2016, scientists reported identifying a set of 355 genes from the last universal common ancestor (LUCA) of all organisms living on Earth.

The term gene was introduced by Danish botanist, plant physiologist and geneticist Wilhelm Johannsen in 1909.

A geneticist is a biologist who studies genetics, the science of genes, heredity, and variation of organisms.

Some genetic traits are instantly visible, such as eye color or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that constitute life.

Eye color is an inherited trait influenced by more than one gene.

These genes make up different DNA sequences called genotypes.

So, typically, one refers to an individual's genotype with regard to a particular gene of interest and the combination of alleles the individual carries (see homozygous, heterozygous).

The term gene was introduced by Danish botanist, plant physiologist and geneticist Wilhelm Johannsen in 1909.

He is best known for coining the terms gene, phenotype and genotype, and for his 1903 "pure line" experiments in genetics.

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

Genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity in organisms.

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.

In genetics, a locus (plural loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located.

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.

He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while apparently unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation theory of evolution.

Some genetic traits are instantly visible, such as eye color or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that constitute life.

Another significant historic event in biochemistry is the discovery of the gene, and its role in the transfer of information in the cell.

Some genetic traits are instantly visible, such as eye color or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that constitute life.

They have been described as "organisms at the edge of life" because they possess genes, evolve by natural selection, and replicate by creating multiple copies of themselves through self-assembly.

The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic trait.

The inheritable unit that may influence a trait is called a gene.

The existence of discrete inheritable units was first suggested by Gregor Mendel (1822–1884).

(In the preceding example, the green trait, which seems to have vanished in the first filial generation, is recessive and the yellow is dominant.) He published his work in 1866, demonstrating the actions of invisible "factors"—now called genes—in predictably determining the traits of an organism.

An automated version of the Sanger method was used in early phases of the Human Genome Project.

The Human Genome Project (HGP) was an international scientific research project with the goal of determining the base pairs that make up human DNA, and of identifying and mapping all of the genes of the human genome from both a physical and a functional standpoint.

Evolutionary biologists have subsequently modified this concept, such as George C. Williams' gene-centric view of evolution.

The gene-centered view of evolution, gene's eye view, gene selection theory, or selfish gene theory holds that adaptive evolution occurs through the differential survival of competing genes, increasing the allele frequency of those alleles whose phenotypic trait effects successfully promote their own propagation, with gene defined as "not just one single physical bit of DNA [but] all replicas of a particular bit of DNA distributed throughout the world".

The experiments of Benzer using mutants defective in the rII region of bacteriophage T4 (1955–1959) showed that individual genes have a simple linear structure and are likely to be equivalent to a linear section of DNA.

The T4 rII system is an experimental system developed in the 1950s by Seymour Benzer for studying the substructure of the gene.

The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing and turned it into a routine laboratory tool.

DNA sequencing may be used to determine the sequence of individual genes, larger genetic regions (i.e. clusters of genes or operons), full chromosomes, or entire genomes of any organism.

He proposed an evolutionary concept of the gene as a unit of natural selection with the definition: "that which segregates and recombines with appreciable frequency."

A unit of selection is a biological entity within the hierarchy of biological organization (for example, an entity such as: a self-replicating molecule, a gene, a cell, an organism, a group, or a species) that is subject to natural selection.