Reproduction Heredity and Punnett Square Menu • Recap WS 6 • PowerPoint Slides – Mendel and Punnett • Activity 1 – Practice • Activity 2 – Consolidate Recapitulation • Why do we share common traits with our parents? • Why we share different traits from each parent? – BUT: Sometimes we don’t share some traits Mendelian Genetics Gregor Johann Mendel (1822 – 1884) • Austrian monk • Cultivated and studied pea plants in the garden of his monastery • Mendel’s Laws of Inheritance: – We inherit one of two forms of a gene from each parent – Inheritance of a gene is independent (50-50 chance) • We inherit two forms of a gene – one from each parent Why do we express one form and not the other? Dominant and Recessive genes • Dominant gene: the gene that masks the other gene and expresses itself • Recessive gene: can only express itself when both genes are recessive “How do we find out the combinations that are possible?” LINK The Punnett square • Created by Reginald Crundall Punnett (1875 – 1967) • A British geneticist • How to use a Punnett square? – Refer to example Activity 1 (5 minutes) • Use the Punnett square to determine the different combinations of traits inherited • What is the probability for each trait? – probability and percentage Activity 2 - Consolidation Farmer Bob grows two types of corn – Purple (dominant) and Yellow (recessive). He would like to grow a new type of corn that is 3:1 Purple to Yellow. Which corn should he cross? • Pair up to discuss • Use the Punnett square to help Farmer Bob solve his problem Activity 2 – EXTENSION (optional) • How can he know if the Purple or Yellow corn he is using is a carrier and not dominant (both genes)?
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