TECHNIQUE 2 aental geneation () Stamens Capel 3 4 ESULTS Fist filial geneation offsping (F ) 5 2
EXEIMENT Geneation (tue-beeding paents) uple flowes White flowes F Geneation (hybids) All plants had puple flowes F 2 Geneation 705 puple-floweed plants 224 white-floweed plants 3 4
Allele fo puple flowes Locus fo flowe-colo gene Homologous pai of chomosomes Allele fo white flowes 5 Geneation Aeaance: uple flowes White flowes Genetic makeup: Gametes: p F Geneation Aeaance: Genetic makeup: Gametes: F 2 Geneation uple flowes p p p 3 6
henotype Genotype uple (homozygous) 3 uple (heteozygous) 2 uple (heteozygous) White (homozygous) atio 3: atio :2: 7 TECHNIQUE Dominant phenotype, unknown genotype: o? ecessive phenotype, known genotype: edictions If If o p p p p p ESULTS o All offsping puple offsping puple and offsping white 8
EXEIMENT Geneation YY yy Gametes Y y F Geneation edictions Hypothesis of dependent assotment Yy Hypothesis of independent assotment edicted offsping of F 2 geneation /2 /2 Y y Y /2 /2 y YY Yy Yy yy o Y Y y Y Y y y YY YY Yy Yy YY YY Yy Yy Yy Yy yy yy 3 henotypic atio 3: y Yy Yy yy yy 9 /6 3 /6 3 /6 /6 ESULTS 35 08 0 32 henotypic atio 9:3:3: henotypic atio aoximately 9:3:3: 9 Segegation of alleles into eggs Segegation of alleles into spem / 4 / 4 / 4 / 4 0
Geneation ed C C White C W C W Gametes C C W F Geneation ink C C W C Gametes C W F 2 Geneation / C 2 / C C W 2 C C C C W / C W 2 C C W C W C W Allele I A I B Cabohydate i none (a) The thee alleles fo the ABO blood goups and thei associated cabohydates A B Genotype I A I A o I A i ed blood cell aeaance henotype (blood goup) A I B I B o I B i B I A I B AB ii (b) Blood goup genotypes and phenotypes O 2
BbCc BbCc / 4 BC / 4 bc / 4 BC / 4 bc / 4 Bc / 4 bc BBCC BbCC BBCc BbCc BbCC bbcc BbCc bbcc / 4 Bc BBCc BbCc BBcc Bbcc / 4 bc BbCc bbcc Bbcc bbcc 9 : 3 : 4 3 AaBbCc AaBbCc / 8 / 8 / 8 / 8 / 8 / 8 / 8 henotypes: Numbe of / 64 6 / 5 64 / 20 64 / 5 64 / 6 64 / 64 / 64 dak-skin alleles: 0 2 3 4 5 6 4
5 Key Male Female Affected male Affected female Mating Offsping, in bith ode (fist-bon on left) st geneation (gandpaents) Ww ww ww Ww 2nd geneation (paents, aunts, and uncles) 3d geneation (two sistes) Ww ww ww Ww Ww ww WW o Ww ww Widow s peak No widow s peak (a) Is a widow s peak a dominant o ecessive tait? st geneation (gandpaents) Ff Ff ff Ff 2nd geneation (paents, aunts, and uncles) FF o Ff ff ff Ff Ff ff 3d geneation (two sistes) ff FF o Ff Attached ealobe Fee ealobe (b) Is an attached ealobe a dominant o ecessive tait? 6
Amniotic fluid withdawn Fetus Centifugation Fetus lacenta Uteus Cevix lacenta Choionic villi Suction tube inseted though cevix Fluid Fetal cells Seveal hous Seveal weeks Biochemical tests Seveal hous Fetal cells Seveal weeks Kayotyping Seveal hous (a) Amniocentesis (b) Choionic villus sampling (CVS) 7 Degee of dominance Desciption Example Complete dominance of one allele Heteozygous phenotype same as that of homozygous dominant Incomplete dominance of eithe allele Heteozygous phenotype intemediate between the two homozygous phenotypes C C C C W C W C W Codominance Heteozygotes: Both phenotypes expessed I A I B Multiple alleles leiotopy In the whole population, some genes have moe than two alleles One gene is able to affect multiple phenotypic chaactes ABO blood goup alleles I A, I B, i Sickle-cell disease 8
elationship among genes Desciption Example Epistasis One gene affects the expession of anothe BbCc BC BC bc Bc BbCc bc bc Bc bc olygenic inheitance A single phenotypic chaacte is affected by two o moe genes AaBbCc 9 : 3 : 4 AaBbCc 9