Gregor Mendel 1822 1884 The Father of Genetics

Gregor Mendel (1822 -1884) The Father of Genetics copyright cmassengale © Fall 2005, Pflugerville ISD, 7 th Grade 1

Gregor Johann Mendel §Austrian monk §Studied the inheritance of traits in pea plants §Developed the laws of inheritance §Mendel's work was not recognized until the turn of the 20 th century © Fall 2005, Pflugerville ISD, 7 th Grade 2

Gregor Johann Mendel §Between 1856 and 1863, Mendel cultivated and tested thousands of pea plants §He found that the plants' offspring retained traits of the parents copyright cmassengale © Fall 2005, Pflugerville ISD, 7 th Grade 3

Particulate Inheritance §Mendel stated that physical traits are inherited as “particles” §Mendel did not know that the “particles” were actually Chromosomes & DNA copyright cmassengale © Fall 2005, Pflugerville ISD, 7 th Grade 4

Why Peas? Talk with your shoulder buddy for a minute and discuss why you think Mendel choose peas as his primary mode of experimenting! © Fall 2005, Pflugerville ISD, 7 th Grade

Why peas, Pisum sativum? §Can be grown in a small area §Produce lots of offspring §Produce pure plants when allowed to selfpollinate several generations §Can be artificially cross -pollinated copyright cmassengale © Fall 2005, Pflugerville ISD, 7 th Grade 6

Science Humor © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel and His Peas • Mendel tested 7 traits: 1. 2. 3. 4. 5. 6. 7. Flower color Flower position Seed color Seed shape Pod color Plant height http: //www. fieldmuseum. org/exhibits/traveling_mendel. htm © Fall 2005, Pflugerville ISD, 7 th Grade

Video Break… • http: //youtu. be/Ev. R _Sdm 1 or. U Unit A : Chapter 1 : Section 1 © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel and His Peas • Mendel crossed flowers that were truebreeding for each characteristic. • He crossed a purple (PP) flowered plant with a white (pp) flowered plant. (Parent Generation) http: //biology. kenyon. edu/courses/biol 114/KH_lecture_images/Mendel. html © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel and His Peas • Where did the white color go? ? © Fall 2005, Pflugerville ISD, 7 th Grade White Parent • The first generation (F 1) of plants all had purple flowers. (pp) Purple Parent (PP) (Pp)

Mendel and His Peas • In the second generation (F 2) he had 3 purple flowered plants, and 1 white flowered plant. © Fall 2005, Pflugerville ISD, 7 th Grade Purple Parent (Pp) • Mendel took two of his first generation (F 1 x F 1) purple flowered plants and crossed them together. (PP) (Pp) (pp)

Mendel and His Peas • Mendel noticed in the first generation, all of the white flowers seemed to disappear. – He called this a recessive trait. – The white color faded into the background at first, then it showed up in the next generation when he pollinated the flowers. © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel and His Peas • The color (purple) that seemed to mask over the recessive color was named the dominant trait. © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel’s Conclusions… 1) Law of Independent Assortment – inheritance of one trait had NO EFFECT on the inheritance of another trait – When he crossed two plants with different traits (flower color and pea shape) he found the inheritance of one trait did NOT influence the inheritance of the other Unit A : Chapter 1 : Section 1 © Fall 2005, Pflugerville ISD, 7 th Grade

Mendel’s Conclusions… 2) Law of Segregation – Alleles of a gene separate during meiosis and each gamete receives only one allele for each trait Unit A : Chapter 1 : Section 1 © Fall 2005, Pflugerville ISD, 7 th Grade

Top 5 Biology Song… • http: //youtu. be/2 xp. Tz 7 SUbnc Unit A : Chapter 1 : Section 1 © Fall 2005, Pflugerville ISD, 7 th Grade