- Karyotypes show the 23 pairs of chromosomes in human cells, with autosomes making up the first 22 pairs and sex chromosomes determining gender as the 23rd pair (XX female, XY male) - Pedigree charts show the genetic history and inheritance of traits in a family over generations using symbols to represent individuals and their genotypes - Traits can be dominant, recessive, or sex-linked (located on the X chromosome); the chance of offspring inheriting traits can be determined using Punnett squares - Down syndrome is identified via karyotype as having an extra copy of chromosome 21, giving 47 total chromosomes rather than the typical 46

1. Human Heredity

9. Pedigree Chart of a Dominant Trait The father does not have the dominant disease so he must have 2 recessive alleles; his genotype is hh The son has the dominant disease so he has to have at least one dominant allele. Is his genotype HH or Hh? One allele came from his father so his genotype is Hh.

10. Pedigree Chart of a Dominant Trait hh HH Hh What are the chances that future offspring of this couple will have this dominant disease? Use the genotypes of the parents to draw a punnett square.

11. Pedigree Chart of a Dominant Trait hh HH Hh All of the offspring have the dominant allele so 100% of their future children will have this dominant disease. H H h Hh Hh h Hh Hh

13. Pedigree Chart of a Recessive Trait She must have 2 recessive alleles to have this disease. Her genotype is cc. The dad does not have this recessive disease so his genotype is either CC or Cc. Since he passed on one recessive allele to his daughter, his genotype is Cc.

14. Pedigree Chart of a Recessive Trait What are the chances that future offspring of this couple will have this recessive disease? Use the genotypes of the parents to draw a punnett square. Cc Cc cc

15. Pedigree Chart of a Recessive Trait Cc Cc cc C c C CC Cc c Cc cc Only 1 out of 4 offspring have the recessive disease (cc). There is a 25% chance of future offspring having the disease.

22. Practice What percentages can be expected in the offspring of a cross between a female carrier for color blindness and a male with a normal color vision? Show your work with a punnett square.

23. Practice What percentages can be expected in the offspring of a cross between a female carrier for color blindness and a male with a normal color vision? Color blindness is a recessive trait attached to the X chromosome. A female carrier means heterozygous. female carrier X B X b male with normal vision X B Y X B X b Y X B Y X b Y X B X B X B X B X b 25% colorblind males 25% carrier females 25% normal males 25% normal females