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 DominanceInheritance 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

R R

R' RR' RR'

R' RR' 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 shapedXY – Male, Y is J or hook shaped

Humans – 46 chromosomesAutosomes – 44 chromosomesSex Chromosomes – 2 chromosomes

Drosophila – 8 chromosomesAutosomes – 6 chromosomesSex Chromosomes – 2 chromosomes

Traits controlled by genes located on sex chromosomes

Those carried on the X and Y chromosome1. 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