Genotype (遺傳子型, English: genotype) is a genetic term that refers to the genetic characteristics expressed in cells, organisms, and individuals. In general, it refers to a trait that characterizes a species. It is also called genotype. A phenotype is a concept that contrasts with the genotype. A phenotype refers to a characteristic that occurs through interaction with the natural environment during the development and growth of an organism and is not inherited. On the other hand, due to mutations, etc., new genetic traits that are not inherited from the parental generation may be generated. In epigenetics, the occurrence of this non-inherited DNA is identified as an atypical genetic trait. Cancer is a representative example of such epigenetic genetic trait development.
Genotype and gene sequence
The genome is the total base sequence of all genes in an organism, and is the sum of the nearly complete genetic information of an organism. The genome is not only different from species to species, but also slightly different for each group and individual. These differences arise from differences in the nucleotide sequences present in the genome. Numerous alleles randomly sampled from a population's gene pool are combined to form an individual's genome. As a result, genetic diversity can be found in almost all living things.
The human genome consists of about 3 billion pairs (6 billion bp) of nucleotide sequences. The length of DNA contained in one human cell reaches 2 m. The genome of a typical virus consists of 10,000 nucleotide sequences, and the genome of Escherichia coli consists of 4.5 million nucleotide sequences. However, organisms that are generally known to be more complex do not have larger genomes. A lily's DNA is 18 times the size of a human. Even in organisms with such a very simple structure, genetic traits consist of very diverse alleles.
Mendelian and Genotype
The meaning of these words in biology is closely related to the laws Mendel discovered in his experiments with pea breeding. One of Mendel's laws is that phenotypic features that appear in one parental generation do not appear mixed in the next. For example, when seeds obtained by fertilization of white-flowering peas and frequent-flowering peas are planted, as we might have guessed, pale pink peas are not produced (next picture). Mendel explained this phenomenon using the concept of a dominant or recessive genetic element (Vererbungsfaktor). Here, the word genetic element can be understood as having a similar meaning to the gene introduced in the early 20th century. The dominant or recessive genetic element, according to Mendel, does not represent the superficial characteristics of the pea. The distinction between the superficial features of these genetic traits and the internal genetic elements was asserted by Mendelians in the 1880s, and the concepts of genotype and phenotype were already used at this time, but they did not receive much attention in academia. In the 1940s, the existence of genes was concretely proved by the discovery of the chemical composition of hereditary traits, and the concepts of genotype and phenotype were also universally used in biology.
Extended Interpretation of the Neo-Darwinian Phenotype
The term phenotype, which was used only to refer to the external characteristics of an organism, is widely interpreted by neo-Darwinists who are trying to develop Darwin's theory of evolution in connection with genetics. According to this extended interpretation, not only the external form and characteristics of an organism, but also the biochemical structure and ecology of the organism are included in the phenotype category. with the same genotype