CHAPTER 9 Patterns of Inheritance PowerPoint Lecture Slides for Essential Biology Second Edition Essential Biology with Physiology Neil Campbell Jane Reece and Eric Simon Presentation prepared by Chris C Romero Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings BIOLOGY AND SOCIETY TESTING YOUR BABY Genetic testing Allows expectant parents to test for possibilities in their unborn child Includes amniocentesis and CVS Has risks associated with it Figure 9 1 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings HERITABLE VARIATION AND PATTERNS OF INHERITANCE Wild type traits are traits most commonly found in nature Figure 9 2 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 1 Parents Parents Wild type Offspring All Wild type Wild type Wild type Firstgeneration offspring Sky blue wild type All Matings a Offspring from the mating of two wild type birds Secondgeneration offspring 3 4 Wild type and 1 4 Sky blue b Two generations of offspring from the mating of a wild type with a sky blue bird Figure 9 3 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Gregor Mendel Was the first person to analyze patterns of inheritance Deduced the fundamental principles of genetics Figure 9 4 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings In an Abbey Garden Mendel studied garden peas These plants are easily manipulated These plants can self fertilize Stamen Carpel Figure 9 5 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 2 Mendel carried out some crossfertilization P F1 F2 p 145 White 1 Removed stamens from purple flower Stamens Carpel Parents P 2 Transferred pollen from stamens of white flower to Purple carpel of purple flower 3 Pollinated carpel matured into pod 4 Planted seeds from pod Offspring F1 Figure 9 4 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings He also created true breeding varieties of plants self fertilization produced offspring all identical to the parent Mendel then crossed two different true breeding varieties creating hybrids Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Mendel s Principles of Segregation Mendel performed many experiments He tracked several characteristics in pea plants from which he formulated several hypotheses During the production of gametes each ovum or sperm receives only one from each pair of chromosomes Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 3 Dominant Flower color Purple Recessive Recessive Dominant Pod shape Inflated Constricted Pod Color Green Yellow Stem length Tall White Flower position Axial Terminal Seed color Yellow Green Seed shape Round Wrinkled Dwarf Figure 9 7 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Monohybrid Crosses A monohybrid cross is a cross between parent plants that differ in only one characteristic P Generation true breeding parents Purple flowers White flowers All plants have purple flowers F1 Generation Fertilization among F1 plants F1 F1 F2 Generation 3 4 of plants have purple flowers 1 4 of plants have white flowers a Mendel s crosses tracking one characteristic flower color Figure 9 8a Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Mendel developed four hypotheses from the monohybrid cross There are alternative forms of genes now called alleles For each characteristic each organism has two genes Gametes carry only one allele for each inherited characteristic Alleles can be dominant or recessive Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 4 An explanation of Mendel s results including a Punnett square Genetic makeup alleles pp PP P plants Gametes All P 1 2 P All p F1 plants hybrids Gametes All Pp F2 plants Phenotypic ratio 3 purple 1 white Eggs 1 2 P P PP p p Sperm p Pp Pp pp Genotypic ratio 1 PP 2 Pp 1 pp b Explanation of the results in part a Figure 9 8b Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Phenotype An organism s physical traits ex tall short green etc Genotype An organism s genetic makeup ex TT Tt tt Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Mendel s principle of segregation Pairs of alleles segregate separate during gamete formation the fusion of gametes at fertilization creates allele pairs again Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 5 Genetic Alleles and Homologous Chromosomes Homologous chromosomes Have genes at specific loci Have alleles of a gene at the same locus Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Homologous chromosomes Gene loci Dominant allele a P P PP Genotype Homozygous for the dominant allele a aa Homozygous for the recessive allele B b Recessive allele Bb Heterozygous Figure 9 9 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Homozygous When an organism has identical alleles for a gene Heterozygous When an organism has different alleles for a gene Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 6 Mendel s Principle of Independent Assortment Two hypotheses for gene assortment in a dihybrid cross Dependent assortment Independent assortment Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings b Hypothesis Independent Assortment a Hypothesis Dependent assortment P Generation RRYY rryy RRYY Gametes RY ry rryy ry Gametes RY RrYy F1 Generation RrYy 1 Eggs Eggs 1 1 2 2 RY ry 1 2 Sperm RY 1 2 1 ry F2 Generation 1 1 rY Ry RrYY RRYy 4 RrYy RY 1 Sperm 4 RrYY rrYY RrYy rY 1 RRYy Rryy rrYy Rryy rryy 4 Ry 1 RrYy RrYy RRyy rrYy Actual results contradict hypothesis 4 RRYY 4 4 ry 4 1 RY 4 ry 9 3 Yellow round 16 Green round 16 3 16 1 16 Actual results support hypothesis Yellow wrinkled Green wrinkled Figure 9 10 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings Mendel s principle of independent assortment Each pair of alleles segregates independently of the other pairs during gamete formation Blind Phenotypes Genotypes Black coat normal vision B N Black coat blind PRA B nn Blind Chocolate coat normal vision bbN Chocolate coat blind PRA bbnn a Mating of heterozygotes black normal vision Phenotypic ratio of offspring BbNn 9 black coat normal vision 3 black coat blind PRA b BbNn 3 chocolate coat normal vision 1 chocolate coat blind PRA Figure 9 11 Copyright 2004 Pearson Education Inc publishing as Benjamin Cummings 7 A dihybrid cross with two parents heterozygous for both