Learning assignment on Mendels laws 17-18.pdf - Learning...

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Learning Assignment on Mendel's Laws 1 BIOL10521 LEARNING ASSIGNMENT: MENDEL'S LAWS Purpose of this Learning Assignment ALL students should read through this learning assignment. Mendel’s laws will only be covered briefly in week 5. Most students will already have come across Gregor Mendel's experiments and the laws he derived from them. For those students this learning assignment will be useful revision before more difficult aspects of genetics are covered in the lectures. Other students may not be familiar with the basic concepts of eukaryotic genetics in which case they should study this learning assignment carefully and read the appropriate material in Biology 10/11e , and/or iGenetics 3e . At the end of this learning assignment there are problems to test your understanding of the material; answers to these problems will be available on Blackboard in week 6. Intended Learning Outcomes (ILOs) You should: know how Mendel used monohybrid and dihybrid crosses to derive his laws be able to make use of Punnett squares to solve genetics problems understand the multiplication and addition rules of probability and how they can be applied to problems in Mendelian genetics Essential Reading Biology 10/11e Ch 14 Mendelian Genetics or Life: the Science of Biology 10e Ch 12 Inheritance, Genes & Chromosomes Additional Reading iGenetics 3e Ch 11 Mendelian Genetics Introduction When Gregor Mendel began his plant breeding experiments in 1854, little was known about the mechanisms of heredity. Of course it was known that "like beget like" that offspring resemble their parents, to some extent . Most of Mendel's scientific contemporaries thought that characteristics were passed from one generation to the next by a form of blending inheritance so that the parents' characteristics were blended or averaged in their offspring. Mendel's work is considered the foundation of modern genetics because he showed that factors controlling characteristics what we now call genes pass unaltered from generation to generation in a predictable way. Mendel's experiments Mendel used the garden pea ( Pisum sativum ) in his experiments, using varieties that differed in seven character traits (e.g. seed colour and stem height). Each of these character traits existed in two forms (e.g. yellow or green seeds) and each of these forms was true-breeding (or pure-breeding) i.e. when the plants are allowed to self-fertilise they always produced offspring with the same trait over many generations. What true-breeding implies is that the each variety is homozygous at the gene locus responsible for the trait. He then carried out a series of systematic crosses (matings) between the different varieties of pea plants.