Post on 18-Dec-2015
Chromosome Chromosome Theory of Theory of
InheritanceInheritance
Chromosome TheoryChromosome Theory
Today’s understanding:Today’s understanding:Genes, which determine genetic Genes, which determine genetic traits, are located on chromosomestraits, are located on chromosomes
Historical Evidence:Historical Evidence: SuttonSutton MorganMorgan BridgesBridges
X – Linked Traits X – Linked Traits HUMAN EXAMPLEHUMAN EXAMPLE
Autosomal InheritanceAutosomal Inheritance Genes for these traits on #1Genes for these traits on #1 22 22 Both ♂ & ♀ have two genes for every Both ♂ & ♀ have two genes for every
traittrait
X-linked InheritanceX-linked Inheritance X- Linked traitX- Linked trait – traits whose gene is – traits whose gene is
located on the “X” chromosome, located on the “X” chromosome, thereforetherefore Females (XX) have two genesFemales (XX) have two genes Males (XY) only have one……Males (XY) only have one……
Human Sex Human Sex ChromosomesChromosomes
Some X-linked TraitsSome X-linked Traits
H = normal blood clottingH = normal blood clottinghh = hemophilia = hemophilia
D = normal muscular developmentD = normal muscular developmentd = muscular dystrophyd = muscular dystrophy
C = normal color visionC = normal color visioncc = color blindedness = color blindedness
Possible Genotypes of Possible Genotypes of BIO SCI230BIO SCI230 ♀ ♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype
phenotypephenotype
Possible Genotypes of Possible Genotypes of SCI 230SCI 230♀♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype HomozygoHomozygo
us us DominantDominant
phenotypephenotype Normal Normal Color Color VisionVision
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♀♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype HomozygoHomozygo
us us DominantDominant
heterozygoheterozygousus
phenotypephenotype Normal Normal Color Color VisionVision
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♀♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype HomozygoHomozygo
us us DominantDominant
heterozygoheterozygousus
phenotypephenotype Normal Normal Color Color VisionVision
Normal Normal but but
“carrier”“carrier”
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♀♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype HomozygoHomozygo
us us DominantDominant
heterozygoheterozygousus
HomozygHomozyg..
RecessivRecessivee
phenotypephenotype Normal Normal Color Color VisionVision
Normal Normal but but
“carrier”“carrier”
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♀♀
C CC C
† †† †C C cc
† †† † cc cc
† †† †genotypegenotype HomozygoHomozygo
us us DominantDominant
heterozygoheterozygousus
HomozygHomozyg..
RecessivRecessivee
phenotypephenotype Normal Normal Color Color VisionVision
Normal Normal but but
“carrier”“carrier”
Color Color blind!blind!
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♂♂
C C
† † γγ
cc
† † γγGenotypeGenotype
phenotypephenotype
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♂♂
C C
† † γγ
cc
† † γγGenotypeGenotype
hemizygoushemizygous
dominantdominant
phenotypephenotype
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♂♂
C C
† † γγ
cc
† † γγGenotypeGenotype
hemizygoushemizygous
dominantdominant
phenotypephenotype normal normal color visioncolor vision
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♂♂
C C
† † γγ
cc
† † γγGenotypeGenotype
hemizygoushemizygous
dominantdominanthemizygoushemizygous
recessiverecessive
phenotypephenotype normal normal color visioncolor vision
Possible Genotypes of Possible Genotypes of SCI 230 SCI 230 ♂♂
C C
† † γγ
cc
† † γγGenotypeGenotype
hemizygoushemizygous
dominantdominanthemizygoushemizygous
recessiverecessive
phenotypephenotype normal normal color visioncolor vision Color blindColor blind!!
HINTHINT(for working problems w X-(for working problems w X-
linkage)linkage)
RECORD THE SEX RECORD THE SEX CHROMSOMESCHROMSOMES
of BOTH PARENTS !! of BOTH PARENTS !!
Sample ProblemSample Problem
A carrier for hemophilia marries a A carrier for hemophilia marries a normal male.normal male.
1.1. What is the probability that their What is the probability that their daughter is a hemophiliac? daughter is a hemophiliac?
2.2. What is the probability that their What is the probability that their son is a hemophiliac?son is a hemophiliac?
3.3. What is the probability that their What is the probability that their daughter is a carrier?daughter is a carrier?
4.4. What is the probability that their What is the probability that their son is a carrier?son is a carrier?