1. Mendelian Inheritance of Human Traits

2. Pedigree A PEDIGREE is a graphic representation of family inheritance
Similar to a family tree
Follows the inheritance a single trait
E.g. color blindness
Generations are marked with Roman numerals
I, II, III, IV, V

4. Pedigree Symbols Male Mating Siblings Affected Female Carrier
(Heterozygous)
Consanguineous
Mating
Death
Dizygotic Twins
Monozygotic Twins

5. Pedigree How many generations? How many females? How many males?
How many great grandchildren?
Who has the disease?

6. Simple Recessive Heredity
Most genetic disorders are caused by recessive alleles
You must have TWO copies of the recessive allele to be affected
Examples:
Cystic Fibrosis – build up of thick mucous in the lungs and digestive tract
Tay-Sachs disease – a lipid that the body can’t break down accumulates in the nervous system; death by age 5
Phenylketonuria (PKU) – body can’t break down the amino acid phenylalinine; brain damage can occur without a special diet

7. Simple Dominant Heredity
Some traits are caused by dominant alleles
Only one dominant allele must be inherited for the trait to be present
Examples:
Cleft chin
Widow’s peak
Free/Attached earlobes
Hitchhiker’s Thumb
Huntington’s disease – degeneration of brain and nervous system; death between yrs old

12. Karyotype Karyotype – a picture of a person’s pairs of chromosomes
Can be used to identify an abnormal number of chromosomes or sex determination (XX or XY)

14. Down Syndrome – Trisomy 21

15. Ex. Turner Syndrome
1 in 5000
Usually sterile

16. Turner Syndrome

17. Ex. Edwards Syndrome (Trisomy 18)
Most fetuses abort.
If survives,
50% do not survive past 1 week.
90% do not survive past 1 yr.

18. Tri-18

19. Huntington’s
neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems

20. PKU and Fragile X PKU-unable to break down proteins
Fragile X- mutation in the X chromosome causing mild retardation and autism

21. TaySach –destroys the nervous system neurons/brain and is life threatening
Destroys brain function

22. Codominance in Humans Sickle-cell anemia
A = normal allele a = sickle cell allele
AA = normal
Aa = both normal and sickle cell blood cells
Heterozygous individuals have unique resistance to Malaria
aa = sickle-cell anemia

23. Sickle Cell Anemia: genetic disorder where blood cells are oval shaped causing pain

24. aa AA Aa Normal and Sickle Red Blood Cells Sickle Red Blood Cells
Normal Red Blood Cells aa AA Aa

25. Blood Types
Human blood types exhibit both MULTIPLE ALLELES and CODOMINANCE
IA or IB or i
IA and IB are codominant to each other
i is recessive to both IA and IB

26. Blood Types Blood Type Phenotypes IAIA or IAi= A blood
IBIB or IBi = B blood
IAIB = AB blood
ii = O blood
Blood Type Genotypes
IA IA = A blood
IA i = A blood
IBIB = B blood
IBi = B blood
ii = O blood
IAIB = AB blood

27. Codominance

28. IA IA i i IB IB i i IA IB IA i IB i i i x x IA = A blood IB = B blood
i = O blood IA IA i i IB IB i i x x
A blood
B blood IA IB IA i
AB blood
A blood IB i i i
B blood
O blood

29. Blood Types: Donors/Recipients