Patterns of Heredity and Human Genetics

 Pedigree – made up of a set of symbols that identify males and females, the individuals affected by a trait being studied and family relationships (Family Tree)

Pedigree

 Cystic Fibrosis (CF)  Lethal genetic disorder among whites  Thick mucus in lungs and digestive tract  Defective protein in the plasma membrane

 Tay Sachs Disease  Missing enzymes that breaks down lipids  Causes blindness, progressive loss of movement and mental deterioration

 Phenylketonuria (PKU)  Missing enzyme needed to break down amino acid phenylalanine to a different amino acid tyrosine  Damages central nervous system  Cannot break down milk, results in retardation

 Tongue Rolling  Hapsburg Lip - The lower lip and chin protrude, sometimes forcing the mouth open.  Earlobe (Free-hanging)  Hitchhiker’s Thumb  Thick Lips  Huntingtons Disease  Double Jointedness

 Lethal, appears between ages 30 – 50  Breakdown of portions of the brain

 Incomplete Dominance  Inheritance pattern where the phenotype of a heterozygote is intermediate between those of the 2 homozygotes

 Ex.  RR (Red Flowers) x R’R’ (white flowers) = F1 offspring are pink RR R'RR' R'RR'

 With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together..

 All organisms have:  Autosomes – non-sex chromosomes that carry all characteristics except sex  Sex Chromosomes – two chromosomes that determine sex  XX – Female, X is rod shaped  XY – Male, Y is J or hook shaped

Humans – 46 chromosomes Autosomes – 44 chromosomes Sex Chromosomes – 2 chromosomes Drosophila – 8 chromosomes Autosomes – 6 chromosomes Sex Chromosomes – 2 chromosomes

 Traits controlled by genes located on sex chromosomes

Those carried on the X and Y chromosome 1. Hemophilia – free bleeders (X chromosome) Person lacks the gene needed for clotting of the blood 2. Colorblindness – not being able to determine the difference between colors, usually red and green, usually found in males, caused by recessive gene on X chromosome Both conditions are recessive and appear most often in males. A pedigree chart is used to trace genetic traits in families