Classical genetics is the branch of genetics based solely on visible results of reproductive acts. It is the oldest discipline in the field of genetics, going back to the experiments on Mendelian inheritance by Gregor Mendel who made it possible to identify the basic mechanisms of heredity. Subsequently, these mechanisms have been studied and explained at the molecular level.
Contents
Classical genetics consists of the techniques and methodologies of genetics that predate the advent of molecular biology. A key discovery of classical genetics in eukaryotes was genetic linkage. The observation that some genes do not segregate independently at meiosis broke the laws of Mendelian inheritance, and provided science with a way to map characteristics to a location on the chromosomes. Linkage maps are still used today, especially in breeding for plant improvement.
After the discovery of the genetic code and such tools of cloning as restriction enzymes, the avenues of investigation open to geneticists were greatly broadened. Some classical genetic ideas have been supplanted with the mechanistic understanding brought by molecular discoveries, but many remain intact and in use. Classical genetics is often contrasted with reverse genetics, and aspects of molecular biology are sometimes referred to as molecular genetics.
Basic definitions
At the base of classical genetics is the concept of a gene, the hereditary factor tied to a particular simple feature (or character).
The set of genes for one or more characters possessed by an individual is the genotype. A diploid individual often has two alleles for the determination of a character.
Methods
The first method that help in the study of the classical genetic was the Genetic traits. Mendel’s start the crosses by looking the different shapes, appearance that the peas show after the crosses. The genetic traits are crosses that will show the result of the crosses in parental, F1 and F2. For example: Phenotype and Genotype this terms will show the different appearance in the genes and in the characteristics. This method will divide in two traits that are the Dominant and the Recessive allele. This are the two most common ones that will tell us if it is totally express or is not express completely. This beginning of this method occur when Mendel start the study of traits using peas. Moreover, since the decades pass the model organism change the first time was use with plants and flowers and later they use the fruit fly as one of the most important organism in the classical genetics. The study of traits will also be used to linked-sex (genes in the chromosomes that will tell us the sex) or autosomal (these are genes that can tell more that the sex chromosomal). The experiments improve and know the linkage maps can be used in plants and in other organism to study the chromosomes to proof the location in which they can be found.