Gregor Johann Mendel The Father of Genetics By: Jonathan Fisher
Some Background on Mendel • Gregor Johann Mendel was born on July 20th 1822 in the Austrian empire (now the Czech Republic) and was given the name Johann Mendel. • In his childhood he gardened and studied beekeeping. • From 1840 to 1843 he studied practical and theoretical philosophy as well as physics at the University of Olomouc Faculty of Philosophy. • In 1843 Johann began training to become a priest and took up the name Gregorupon entering Augustinian Abbey of St Thomas in Brno. • In 1853 Mendel was a teacher at the Abby and mostly taught physics
Mendel experiments • Encouraged by professors from his university and collogues from the Abby, Mendel began studying variation among plants in the Abby’s two hectare experimental garden. • He primarily studied pea plants and between 1856 and 1863 cultivated and tested around 29,000 plants! • Mendel cross bred pea plants based on certain phenotypes (physical characteristics) to see what phenotype their offspring would have. • Some of the phenotypes he observed and recorded were: Flower color, Stem size, Pod Color and Type, and the texture of the seeds.
Findings • Through seven years of experimenting and observation Mendel made two monumental discoveries: The Law of Segregation and the Law of Independent Assortment. The Law of Segregation states that every individual possesses a pair of Genes for every phenotype. A single gene comes from each parent and is randomly selected from the two genes they have for the specific trait. Of the two genes that the individual possesses, whichever is dominant will express its phenotype over the recessive one. In order for a recessive gene’s phenotype to be expressed both of the genes present in the individual must be recessive. The PunnettSquare above shows the possible offspring from the two parent’s genes.
Findings • The law of independent assortment states that genes for specific traits are passed down to offspring entirely independent of each other. One trait’s genes have no interaction or influence on other trait’s genes or expression. Mendel noticed, while looking at only one trait, a constant 3:1 trait expression ratio of dominant vs. recessive phenotypes when crossing parents who have both a recessive and dominant gene present. He noticed a 9:3:3:1 ratio when looking at two traits. Upon realizing it was just two 3:1 ratios combine he concluded genes are passed along independent of each other. This opposed the belief of “trait blending” that was popular at that time.
Afterwards. . . . • After completing his experiments and publishing the results and laws as well as presenting them to Natural History Society of Brünn in Moravia in 1865., Mendel received little praise and most of his work was left untouched and unlooked at. • In 1900, however, his research was unearthed by Hugo de Vries and Carl Correns while they performed inheritance experiments as well. • After it was possible to view cell dividing and gamete production Mendel’s laws were proven correct!
Some more information • http://www.youtube.com/watch?v=MWkFxWXHTnw Citation: Mendel Single Trait Experiments | Genetics | Biology. Great Pacific Media, 22 Oct. 2009. Web. 20 May 2011. <http://www.youtube.com/watch?v=MWkFxWXHTnw>
Class Traits Activity • How many people in theroom have a hitch-hikers thumb? • How many people in the room can roll their tongue? • Does anyone know why some people can bend their thumbs back further than others or why some can roll their tongues and others can not? The Answer is Simple: GENES!
Class Traits • Based on the number of students with hitchhiker’s thumbs and rolled tongues which trait do you think is dominant and which one is recessive for each phenotype? • Try to draw a punnett square for each trait showing the possible phenotypes of offspring from differently gene’d parents. • If you know your parents phenotypes for either of these two traits can you figure out what two genes you have?
References GregorMendel, Alain F. Corcos, Floyd V. Monaghan, Maria C. Weber "Gregor Mendel's Experiments on Plant Hybrids: A Guided Study", Rutgers University Press, 1993. "The Mathematics of Inheritance". Online museum exhibition. The Masaryk University Mendel Museum. Retrieved Mar. 20, 2011. GregorMendel. Digital image. Gregor Mendel. Amazing News, 19 July 2011. Web. 15 May 2011. http://news.o2u1.com/528.html Mendel Single Trait Experiments | Genetics | Biology. Great Pacific Media, 22 Oct. 2009. Web. 20 May 2011. <http://www.youtube.com/watch?v=MWkFxWXHTnw>