Recessive inheritance and dominant inheritance
Both parents carry a normal gene (N), and a faulty, recessive, gene (n). The parents, although carriers, are unaffected by the faulty gene. Their offspring are affected, not affected, or carriers. This type of inheritance was first shown by Mendel.
One parent has a single, faulty dominant gene (D), which overpowers its normal counterpart (d), affecting that parent. When the affected parent mates with an unaffected and non-carrier mate (dd), the offspring are either affected or not affected, but they are not carriers.
The Histoy of Genetics
The history of genetics starts with the work of an Augustinian friar called Gregor Mendel and is known as the father of genetics. He’s work in the pea plants was published in 1866, it described what came to be known as mendelian inheritance. For several decades after Mendel’s work, a wide variety of theories of heredity proliferated.
In 1900 marked the rediscovery of Mendel by Carl Correns, Hugo de Vries and Erich von Tschermark, by 1915 the basic principles of Mendelian genetics had been applied to a wide variety of organisms. Thomas Hunt Morgan and his fellow drosophilists, genetics developed the Mendelian-Chromosome theory of heredity, which was widely accepted in 1925.
Alongside experimental work, mathematicians developed the stadistical framework of population genetics, bring genetical explanation into the study of the Evolution.
With the basic patterns of genetic inheritance established, many biologists turned to investigate about the physical nature of the gene. In the 40’s and 50’s experiments pointedto DNA as the portion of chromosomes that held genes. A focus on new model organisms such as viruses and bacteria, along with the discovery of the double helical structur of DNA in 1953, marked the transition to the era of molecular genetics.
The central issues in the 60’s was the regulation of genes expression; by the 70´s gene expression could be controlled and manipulated through genetic engineering. In the las decades of the 20th century, many biologists focused on large-scale genetics progects, sequencing entire genomes.
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