Inherited Change and  Gene TechnologyThe passage of information from parent to offspring                             ALBIO...
• Locus – position on the chromosome          in which the gene resides            *plural: loci• Alleles – a particular v...
• Homozygous – 2 identical alleles of a  gene• Heterozygous – 2 different alleles of a  gene                              ...
• Genotype – alleles possesed by an  organism• Phenotype – observable  characteristics/physical traits of an  organism (re...
• Dominant – when effect on the phenotype of a  heterozygote is identical to its effect in a  homozygote• Recessive – only...
Genetic Diagram (monohybrid                  crosses)•   Let N be the dominant allele for normal pigment.•   Let n be the ...
Genotypes of parent                     N              n                     NN                 Nn            NGenotypes  ...
Genetic Diagram (dihybrid crosses)• Let A be the dominant allele for purple stem and a  recessive green• Let D be the domi...
Genotypes   of parent                    AD        Ad         aD       ad                  AADD       AADd        AaDD    ...
• Sex linkage – related to genes that are  carried on an X chromosome but not on a  Y chromosome• Codominance ?• Multiple ...
Test Crosses• Involves crossing an organism showing  the dominant phenotype with one which is  homozygous recessive to fin...
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02 Passage of Info from Parent to Offspring

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02 Passage of Info from Parent to Offspring

  1. 1. Inherited Change and Gene TechnologyThe passage of information from parent to offspring ALBIO9700/2006JK
  2. 2. • Locus – position on the chromosome in which the gene resides *plural: loci• Alleles – a particular variety of the same gene ALBIO9700/2006JK
  3. 3. • Homozygous – 2 identical alleles of a gene• Heterozygous – 2 different alleles of a gene ALBIO9700/2006JK
  4. 4. • Genotype – alleles possesed by an organism• Phenotype – observable characteristics/physical traits of an organism (resulting from interaction between genotype and environment) ALBIO9700/2006JK
  5. 5. • Dominant – when effect on the phenotype of a heterozygote is identical to its effect in a homozygote• Recessive – only expressed when no dominant allele is present• Codominant – both alleles have an effect on the phenotype of a heterozygous organism ALBIO9700/2006JK
  6. 6. Genetic Diagram (monohybrid crosses)• Let N be the dominant allele for normal pigment.• Let n be the recessive allele for albino.Parent phenotype Heterozygous Normal Heterozygous NormalParent genotype  Nn X NnGametes N n N nPossible offspringgenotype NN Nn Nn nnOffspring phenotype Normal Normal Normal Albino ALBIO9700/2006JK
  7. 7. Genotypes of parent N n NN Nn NGenotypes Normal Normalof parent Nn nn n Normal Albino Ratio of phenotype 3 normal : 1 albino ALBIO9700/2006JK
  8. 8. Genetic Diagram (dihybrid crosses)• Let A be the dominant allele for purple stem and a recessive green• Let D be the dominant allele for cut leaves and d recessive smoothParent phenotype Heterozygous HeterozygousParent genotype  AaDd X AaDdGametes AD Ad aD ad ALBIO9700/2006JK
  9. 9. Genotypes of parent AD Ad aD ad AADD AADd AaDD AaDd AD Purple, Purple, Purple, Purple, cut cut cut cut AADd AAdd AaDd Aadd Ad Purple, Purple, Purple, Purple, Genotype cut smooth cut potato s of AaDD AaDd aaDD aaDd parent aD Purple, Purple, Green, Green, cut cut cut Cut AaDd Aadd aaDd aadd ad Purple, Purple, Green, Green, cut smooth Cut smoothRatio of phenotype 9 purple,cut:3 purple,smooth:3 green,cut:1 green,smooth ALBIO9700/2006JK
  10. 10. • Sex linkage – related to genes that are carried on an X chromosome but not on a Y chromosome• Codominance ?• Multiple alleles – the existence of 3 or more alleles of a gene (eg. determination of A, B, and O blood groups) ALBIO9700/2006JK
  11. 11. Test Crosses• Involves crossing an organism showing the dominant phenotype with one which is homozygous recessive to find out if the dominant genotype is hetero- or homozygous. ALBIO9700/2006JK

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