Pissum sativum in Mendelian Genetics
(Advantages of Pisum satiuvum in the Hybridization Experiments of Gregor Johan Mendel)
Gregor Johan Mendel, the Father of Genetics, used Pisum sativum (garden pea) as the study material for his hybridization experiments. He studied the inheritance pattern of seven pairs of contrasting characters in Pisum sativum for deriving his conclusions.
A combination of luck, scientific aptitude, foresight, mathematical background and most importantly the selection of suitable plant material (i.e., Pisum sativum) for the studies contributed the success of Mendel’s hybridization experiments.
Pisum sativum possesses many advantages as a study material in the hybridization experiment that knowingly or unknowingly helped Mendel to derive a logical conclusion from his crossing experiments. The advantages of Pisum sativum as a study material in hybridization experiments are given below:
Ø Pisum sativum is an annual plant with a short span of life cycle. Thus many generations can be produced within a short period of time.
Introduction to Genetics: Genetics Terminologies
(Concept of Genetics: Definition of Terminologies in Genetics)
What is genetics?
Ø Genetics: Genetics is the study of Heredity and Variation of Inherited Characters.
Ø Heredity: The tendency offspring to resemble their parents is called heredity.
Ø Variation: The tendency of offspring to vary from their parents is called variation.
Ø The term ‘Genetics’ was coined by William Bateson in 1905
Ø Genetics is a relatively young branch of biological science.
Ø The study of genetics started with the work of Gregor Johan Mendel (Father of Modern Genetics)
Ø Today, many modern branches of genetics are there such as Cytogenetics, Molecular Genetics, Phylogenetics, Developmental Genetics and Behavioral Genetics.
(Law of Dominance and Law of Segregation)
Monohybrid cross is a type of hybridization experiment which involves the study of the inheritance of one pair of contrasting character. The alleles of contrasting characters selected in the monohybrid cross will show exact Dominance and Recessive relationships.
In Mendel’s classical experiment, he studied seven pairs of contrasting characters and carefully analyzed the segregation of these characters. Based on to the results from Mendel’s monohybrid cross two Mendelian laws were formulated. They were (1) Law of Dominance and (2) Law of Segregation or Law of Purity of Gametes. In this session, we will discuss Mendel’s original monohybrid cross and his conclusions regarding the results he obtained after the cross.
Mendel selected Pea plants for his hybridization experiments:
Pisum sativum or garden pea was the study material used by Gregor Johann Mendel (the Father of Modern Genetics) for his hybridization experiments. In one of his monohybrid cross, he selected plant height as the character. Plant height in Pisum sativum is controlled by a single gene with two contrasting alleles. The dominant allele of plant height is Tall and he represented it as ‘T’. The recessive allele for the plant height is Dwarf and he represented it as ‘t’. These two phenotypes were morphologically very distinct and can be differentiated very easily.
Procedure of Monohybrid Cross
Ø Mendel selected two pea plants- one a true-breeding (homozygous) tall and the other a true-breeding dwarf.
Ø He generated these true-breeding parent plants by repeated selfing for several generations.
Ø In his experiment, Mendel crossed a homozygous Tall (TT) plant with a homozygous dwarf (tt) plant.
Ø The progenies of the first cross were called as the F1 generation (First filial generation).