14. Pedigrees/ Human Genetics

Fruit Fly- Drosophila melanogaster, used by scientists to study genes and heredity.  Advantages of Fruit Flies  Short Life Span  Small and easy to maintain  8 Chromosomes

 Autosome- 22 pairs of non-sex cells determining traits.  Sex Chromosomes- one pair of chromosomes determining gender. Human Chromosomes- 46 total (23 pairs)

 Karyotype- picture of all the chromosomes lined up during metaphase taken about half way through pregnancy used to determine a chromosomal abnormality. (blood cells) Karyotype

 Male- XY  Female- XX  Sex-Linked Traits- traits caused by genes that are located on the sex chromosomes.  Ex. Color Blindness, Pattern Baldness, Hemophilia  Why Males are affected more than females  X chromosome is larger than Y chromosome so it holds more genes. Both X’s must have gene to be expressed in females whereas only one X in a male must have gene to be expressed. Determining Sex

 Pedigree Analysis- diagram of a family history that shows how one trait is passed through several generations.  *Used by healthcare workers to help parents determine the likelihood of passing on genetic disorders. Pedigree Analysis

 Symbols of a Pedigree  O = Female  = Male   / = Affected female/ male   ___ = Marriage  = Offspring

 Fill in the shaded people with homozygous recessive (rr).  The non-shaded in people will receive at least one capital.  Determine the second letter on the non-shaded in people by looking at parents, siblings and children Rules of a Pedigree