chromosomal basis of inheritance

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Chromosomal Basis of Inheritance. Tracing Heredity through Inheritance of Specific Chromosomes. Sex Determination. Sex Chromosomes : homologous chromosomes that differ in size and genetic composition between males and females. Sex Determination. - PowerPoint PPT Presentation

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  • Chromosomal Basis of InheritanceTracing Heredity through Inheritance of Specific Chromosomes

  • Sex Determination Sex Chromosomes: homologous chromosomes that differ in size and genetic composition between males and females

    Human ChromosomeXYSize and gene numberLarger2142 genesSmaller326 genesGenetic CompositionMultiple genes unrelated to genderSingle gene influences gender: TDF = testis determining factor

  • Sex Determination Autosome: any chromosome that is not a sex chromosome

    Humans have 22 pairs of autosomes and 1 pair of sex chromosomes

  • Human Karyotype showinghomologous chromosome pairs

  • Sex Determination Female Male XX x XYPhenotypic Ratio of Offspring

  • X-linked Genes Hemophilic Male Non-hemophilic Female (father is hemophilic)Phenotypic Ratio of Offspring

  • Terms Specific toSex-linked Genes

    FemalesHomogametic: only X found in gametes

    Can be homozygous or heterozygous for traits on X-chromosomeMalesHeterogametic: either X or Y in gametes

    Hemizygous for traits on the X-chromosome

  • Patterns of InheritanceAutosomal DominantAutosomal RecessiveX-linked Dominant X-linked RecessiveY-Linked Inheritance

  • Pedigree for Huntingtons Disease, an Autosomal Dominant Trait

  • Pedigree for Albinism, an Autosomal Recessive Trait

  • Pedigree for Colorblindness, an X-linked Recessive Trait