Chapter2Mendel's Principles of Heredity
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Sections to study2.1Background:The historical puzzle ofinheritance2.2Mendel's approachtogenetic analysis2.3Mendelianinheritancein humans.2-2
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-2 2.1 Background: The historical puzzle of inheritance 2.1 Background: The historical puzzle of inheritance 2.2 Mendel 2.2 Mendel’s approach to genetic analysis s approach to genetic analysis 2.3 Mendelian Mendelian inheritance in humans. inheritance in humans. Sections to study Sections to study
2.1Background:The historical puzzle ofinheritanceArtificial selection:Purposeful control over mating by choice ofparents for the nextgeneration.An important practice since before recorded history.SelectivebreedingofplantsDomesticationofanimals2-3
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-3 2.1 Background: The historical puzzle of inheritance 2.1 Background: The historical puzzle of inheritance Artificial selection Artificial selection: Purposeful control over mating by choice of : Purposeful control over mating by choice of parents for the next generation. parents for the next generation. An important practice sinc An important practice since before recorded history. e before recorded history. Selective breeding of plants Selective breeding of plants Domestication of animals Domestication of animals
The 2800-yr old Assyrian reliefFig.2.42-4
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-4 The 2800-yr old Assyrian relief Fig. 2.4
By19th century,plant and animal breeders had created manystrains in which offspring often carried a prized traitBreeders could not explain why a valued trait wouldsometimes disappearand thenreappearin only someoffspring.2-5
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-5 By 19th century, plant and animal breeders had created many century, plant and animal breeders had created many strains in which offspring often carried a prized trait. strains in which offspring often carried a prized trait. Breeders could not explain why a valued trait would Breeders could not explain why a valued trait would sometimes disappear and then sometimes disappear and then reappear in only some reappear in only some offspring. offspring
Three basic questions of genetics proposedbyAbbotNappin18371.What is inherited?2.Howis itinherited?3.What is the role of chance in heredity?2-6
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-6 Three basic questions of genetics proposed Three basic questions of genetics proposed by Abbot by Abbot Napp in 1837 in 1837 1. What is inherited? What is inherited? 2. How is it inherited? How is it inherited? 3. What is the role of chance in heredity? What is the role of chance in heredity?
Historical theories of inheritanceOneparent contributesmostfeatures (Nicolaas Hartsoekerin1694).Blended inheritance-parentaltraits become mixed and foreverchanged in offspring.The homunculus2-7Fig.2.6
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-7 Historical theories of inheritance Historical theories of inheritance 1. One parent contributes most One parent contributes most features ( features (Nicolaas Nicolaas Hartsoeker Hartsoeker in 1694). 2. Blended inheritance Blended inheritance – parental parental traits become mixed and forever traits become mixed and forever changed in offspring. changed in offspring. Fig.2.6 The homunculus
Plant hybrid experiments before Mendel1.Thomas Andrew Knight (1797, Britain)Crossbreed gray garden pea with white garden peaParents,PFFirst filial, FSecond filial, FBut he did not calculate the number!(a)Pisumsativum2-8
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-8 Plant hybrid experiments before Mendel Plant hybrid experiments before Mendel 1. Thomas Andrew Knight Thomas Andrew Knight (1797, Britain) (1797, Britain) But he did not calculate the number! But he did not calculate the number! F1 F1 Parents, P arents, P First filial, F ilial, F1 Second filial, F ilial, F2 Crossbreed Crossbreed gray garden pea with garden pea with white garden pea garden pea
2.Charles Victor Naudin (France,his work btn 1854-1865)His main publication is Memoire sur les hybrides du regnevegetal which appeared in Recueil des savants etrangers andwon him the Grand Prize of the Institute of Botany in 1862Reciprocal crosses with the same resultsThe'specific essence'controls the traits.Factors mustgoto differentgametesduringgameteformation2-9
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-9 2. Charles Victor Charles Victor Naudin (France, his work (France, his work btn 1854-1865) Reciprocal crosses Reciprocal crosses with the same results with the same results Factors Factors must go to different gametes must go to different gametes during gamete formation. during gamete formation. The 'specific essence 'specific essence’ controls the traits. controls the traits. His main publication is Mémoire sur les hybrides du règne végétal which appeared in Recueil des savants étrangers and won him the Grand Prize of the Institute of Botany in 1862
2.2 Gregor Mendel's approach to genetic analysisDiscoverer of general principles ofheredity.Performedplanthybrid experimentsto see whether there is a “generallyapplicablelawgoverningtheformation and development ofhybrids"In 1866,hepublished a paper"Experiments on PlantHybridsGregor Mendel(1822-1884)Fig.2.22-10
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 2-10 2.2 Gregor Mendel’s approach to genetic analysis s approach to genetic analysis Discoverer of general principles of heredity. Performed plant hybrid experiments to see whether there is a “generally applicable law governing the formation and development of hybrids”. In 1866, he published a paper “Experiments on Plant Hybrids”. Fig. 2.2 Gregor Mendel (1822-1884)