Chapter 14Overview: Drawing from the Deck of GenesSlide 3Mendel used the scientific approach to identify two laws of inheritanceMendel’s Experimental, Quantitative ApproachLE 14-2Slide 7Slide 8Mendel’s two LawsThe Law of SegregationLE 14-3Slide 12Slide 13Mendel’s ModelSlide 15LE 14-4Slide 17Slide 18Slide 19Slide 20LE 14-5_2Web sites to checkUseful Genetic VocabularySlide 24LE 14-6The TestcrossLE 14-7The Law of Independent AssortmentSlide 29LE 14-8Slide 31The laws of probability govern Mendelian inheritanceThe Multiplication and Addition Rules Applied to Monohybrid CrossesLE 14-9Slide 35Solving Complex Genetics Problems with the Rules of ProbabilityInheritance patterns are often more complex than predicted by simple Mendelian geneticsExtending Mendelian Genetics for a Single GeneGenetics is not as simple as Gregor Mendel concluded, (one gene, one trait).The Spectrum of DominanceSlide 41LE 14-10Incomplete dominance in carnationsCo-Dominance or multiple alleles:The Relation Between Dominance and PhenotypeFrequency of Dominant AllelesMultiple AllelesSlide 48More exceptions to the dominant/recessive rulePleiotropyEpistasis:Extending Mendelian Genetics for Two or More GenesEpistasisAlbinismLE 14-11Human VariationPolygenic InheritanceLE 14-12Environmental effects:Nature and Nurture: The Environmental Impact on PhenotypeSlide 61Temperature Effects on PhenotypeSlide 63Slide 64Integrating a Mendelian View of Heredity and VariationMany human traits follow Mendelian patterns of inheritancePedigree AnalysisLE 14-14aLE 14-14bSlide 70MUTATION: A PERMANENT CHANGE IN THE DNA. When it happens in the gametes it is inheritable. Some mutations are lethal but most are harmless. Mutations are very important because it creates DIVERSITYRecessively Inherited DisordersCystic FibrosisSickle-Cell DiseaseTay-SachsMating of Close RelativesDominantly Inherited DisordersSlide 78Slide 79HypercholesterolemiaSlide 81Multifactorial DisordersGenetic Testing and CounselingCounseling Based on Mendelian Genetics and Probability RulesTests for Identifying CarriersFetal TestingSlide 87LE 14-17aLE 14-17bNewborn ScreeningCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint Lectures for Biology, Seventh EditionNeil Campbell and Jane ReeceLectures by Chris RomeroChapter 14Chapter 14Mendel and the Gene IdeaCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsOverview: Drawing from the Deck of Genes•What genetic principles account for the passing of traits from parents to offspring?•The “blending” hypothesis is the idea that genetic material from the two parents blends together (like blue and yellow paint blend to make green)•The “particulate” hypothesis is the idea that parents pass on discrete heritable units (genes)•Mendel documented a particulate mechanism through his experiments with garden peasCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mendel used the scientific approach to identify two laws of inheritance•Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experimentsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsMendel’s Experimental, Quantitative Approach•Advantages of pea plants for genetic study:–There are many varieties with distinct heritable features, or characters (such as color); character variations are called traits–Mating of plants can be controlled–Each pea plant has sperm-producing organs (stamens) and egg-producing organs (carpels)–Cross-pollination (fertilization between different plants) can be achieved by dusting one plant with pollen from anotherLE 14-2LE 14-2Removed stamensfrom purple flowerTransferred sperm-bearing pollen fromstamens of whiteflower to egg-bearing carpel ofpurple flowerCarpelStamensParentalgeneration(P)Pollinated carpelmatured into podPlanted seedsfrom podExaminedoffspring:all purpleflowersFirstgenerationoffspring(F1)Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Mendel chose to track only those characters that varied in an “either-or” manner•He also used varieties that were “true-breeding” (plants that produce offspring of the same variety when they self-pollinate)Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mendel mated two contrasting, true-breeding varieties, a process called hybridization•The true-breeding parents are the P generation•The hybrid offspring of the P generation are called the F1 generation•When F1 individuals self-pollinate, the F2 generation is producedCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsMendel’s two Laws•1. Law of segregationThe two alleles for a trait segregate during gamete formation and only one allele for a trait is carried in a gamete. The gametes combine at random(In other words:A cell contains two copies of a particular gene, they separate when a gamete is made).•2. Law of Independent AssortmentAlleles from one trait behave independently from alleles for another trait. Traits are inherited independently from one anotherCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Law of Segregation•When Mendel crossed contrasting, true-breeding white and purple flowered pea plants, all of the F1 hybrids were purple•When Mendel crossed the F1 hybrids, many of the F2 plants had purple flowers, but some had white•Mendel discovered a ratio of about three to one, purple to white flowers, in the F2 generationLE 14-3LE 14-3P Generation(true-breedingparents)F1 Generation(hybrids)F2 GenerationPurpleflowersWhiteflowersAll plants hadpurple flowersCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Mendel reasoned that only the purple flower factor was affecting flower color in the F1 hybrids•Mendel called the purple flower color a dominant trait and white flower color a recessive trait•Mendel observed the same pattern of inheritance in six other pea plant characters•What Mendel called a “heritable factor” is what we now call a geneCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsMendel’s Model•Mendel developed a hypothesis to explain the 3:1 inheritance pattern he observed in F2 offspring•These concepts can be related to what we now know