Gene is a fundamental unit or segment of DNA molecule that is essential for heredity. Each one consists of a specific sequence of nucleic acids that can be: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The term was coined by the Danish geneticist and botanist Wilhelm Ludvig Johannsen (1857 – 1927).
The gene has important functions, such as controlling the organism and the metabolic structures and functions of cells. They are located in sequences of non-protein-encoded DNA in an intercalated manner and are called “useless DNA”. It is of great importance for the organism, since it makes up about 97% of the human genome and helps in the proper functioning of genes.
Each organism has a certain number of chromosomes and any change made in their quantity or arrangement of genes can lead to what is known as a genetic mutation, whose occurrence entails the transmission of this change to future generations. When some somatic cells are affected, they can lead to the appearance of some type of cancer.
Genotype is nothing more than the genetic constitution of a cell, individual or organism. In other words, it concerns the internal characteristics of an individual, such as inheritance from their parents. This information is found in the genome, which is the set of chromosomes that characterize each species.
Genetics is the scientific field that studies genes, variations in organisms and heredity. It is divided into the following areas: Classical (Consists of the methods and techniques used before the emergence of molecular biology), Molecular (Directs its studies towards the structure and function of genes at the molecular level), Genomics (It is the most recent field of study of genetics), population and quantitative genetics and genetic ecology (study populations of organisms taken from nature and based on classical genetics).
Genes receive the following classifications: Dominant (it is the one that determines a characteristic to the individual), Recessive (It is only expressed when it is in a double dose, since in the presence of a dominant it becomes inactive), Structural (it gives rise to the structure and functions of proteins and enzymes), Operator (Controls access to RNA), Regulator (Regulates the transcription of other genes) and Lethal (Causes the death of the individual before or shortly after birth).
