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Karyotypes and Pedigrees: Analyzing Human Chromosomes and Inheritance Patterns

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Explore how karyotypes help map human chromosomes and diagnose disorders. Learn about pedigrees and inheritance patterns in human families, including autosomal recessive and dominant disorders.

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Karyotypes and Pedigrees: Analyzing Human Chromosomes and Inheritance Patterns

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  1. Karyotypes

  2. X Y Several methods help map human chromosomes. • A karyotype is a picture of all chromosomes in a cell.

  3. Human Karyotype • To analyze chromosomes, cells arephotographed during mitosis when chromosomes are fully condensed and easy to see. • Chromosomes are cut out of photographs and lined up with homologous chromosome and in order of largest to smallest. • Used to diagnose chromosomal disorders and determine gender.

  4. Karyotype : chromosomes are paired 1 from mom & 1 from dad 23 pairs 46 chromosomes 22 pairs – autosomes 1 pair sex chromosomes 46,XY Normal male

  5. Down syndrome: (Trisomy 21) 47, XX, 21+

  6. Is there something wrong on this karyotype?

  7. Human chromosomes • Let’s look at this again • There are 46 chromosomes (23 homologous pairs) in each somatic cell • 22pairsof autosomes • 1 pairofsex chromosomes • XX = Female, XY = Male • Karyotype- chromosomes are arranged according to shape and size Normal human karyotype

  8. Pedigrees Biology I

  9. Pedigrees analysis • Shows the analysis of inheritance in human families

  10. Most common signs and symbols used in pedigree analysis

  11. Inheritance patterns shown by a pedigree. • Basic patterns of inheritance • autosomal, recessive • autosomal, dominant • X-linked, recessive

  12. Autosomal recessive • e.g., PKU, Tay-Sachs, albinism • Autosomal dominant • e.g., Huntington’s Disease • X-linked recessive • e.g., color-blindness, hemophilia

  13. Autosomal disorders Autosomal disorders are more prevalent in certain geographic regions or cultures Recessive disorders • Cause: recessive alleles • Albinism, Cystic fibrosis, Sickle-cell anemia, Tay-Sachs disease • More common than dominant disorders Dominant disorders • Cause: dominant alleles • Dwarfism (Achondroplasia), Alzheimer’s disease, Huntington’s disease • Less common than recessive disorders

  14. Autosomal Recessive

  15. Autosomal Dominant

  16. X- linked Recessive What is the inheritance pattern? What is the genotype of III-1, III-2, and II-3? What are the odds that IV-5 would have an affected son?

  17. III-1 has 12 kids with an unaffected wife 8 sons - 1 affected 4 daughters - 2 affected Does he have reason to be concerned about paternity?

  18. Sample pedigree - cystic fibrosis What can we say about I-1 and I-2? What can we say about II-4 and II-5? What are the odds that III-5 is a carrier? What can we say about gene frequency?

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