patterns of heredity and human genetics. pedigree – made up of a set of symbols that identify...
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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