1. Mendel and Human Traits

2. Mendelian Inheritance Heterozygous and Homozygous Dominant have the same phenotype Homozygous recessive will have a different phenotype

3. Intermediate Inheritance (Incomplete Inheritance) The heterozygote is an intermediate of the two homozygotes Red (RR) X White (WW) Pink (RW) RR WW RW

4. Pink Flower Ex. RW RR W W RR - Red WW - White RW - Pink All Offspring are pink

5. Pink Flower Ex.(cont.) RRRW WW RW W R RR - Red WW - White RW - Pink 1/4 = Red 1/2 = Pink 1/4 = White

6. Codominance Sickle Cell Anemia –Blood cells are shaped like a sickle or half-moon –The sickled cells cause clots Heterozygotes have some normal and some sickled cells SS = Sickeled cells RR = Regular cells SR = Some regular, some sickled SR SS R R

7. Multiple Alleles Sometimes there are more than two alleles for each trait –Ex. Blood types A B O AB The alleles: –A = I A –B = I B –O = i

8. Multiple Alleles (cont.) Blood type is determined by the surface proteins on a blood cell Proteins are determined by what alleles the person has

9. Multiple Alleles (cont.) A O B AB

10. Multiple Alleles (cont.) GenotypesSurface Proteins Phenotype I A I A, I A iAA I B I B, I B iBB I A I B AB iiO

11. Multiple Alleles (cont.) Can a man with type A blood and a woman with type AB blood have a daughter with type B blood? I A IAiIAi I A I B IBiIBi IAIA i IBIB IAIA I A IAIAIAIA I A I B IAIBIAIB IAIA IAIA IBIB IAIA

12. Inheritance in Humans

13. Pedigrees A family tree that records and traces traits in a family

14. Gender –Males = Squares –Females = Circles Relationship –A line connecting = marriage

15. Relationships Vertical lines = parents to children Each row = one generation –Roman numerals (I,II,III, etc.) Individuals (1,2,3,4, etc.) Slash = death

16. Phenotype Shaded circle of square = A person who has the trait being studied Unshaded = Does not have trait Half-shaded = carrier or heterozygote

17. Practice

18. Answers Parents Children/Siblings Death 1 2 2 31 I II

19. Used to determine genotype Shaded = attached earlobes (recessive trait) Label the genotypes! F = free earlobes, f = attached earlobes

20. Used to determine genotype Shaded = attached earlobes (recessive trait) Label the genotypes! F = free earlobes, f = attached earlobes Ff F ? Ff ffF? Ff F ? Ff

21. Can predict offspring Genotype What is the percent chance that the next child in generation III will have attached earlobes? Ff F ? Ff ffF? Ff F ? Ff

22. Use a Punnett Square FFFf ff Ff f F 25% chance for attached earlobes

23. Diseases caused by recessive alleles Cystic Fibrosis –Defect in cell membrane protein –Develop a thick mucus in lungs and digestive tract Tay-Sachs –No enzyme that breaks down lipids –Lipids build up nervous tissue => Brain damage Phenylketonuria (PKU) –No enzyme to change phenylalanine into tyrosine –Build up of phenylalanine => Brain Damage

24. Dominant Allele diseases Huntington ’ s Disease –Braek down of brain tissue Achondroplasia –A form of dwarfism Some forms of blindness

25. Dominant Disorders Most of the diseases caused by dominant alleles are lethal in Heterozygotes The individuals die before they can reproduce Low frequency of these alleles (<99.99%)

26. Recessive Disorders Recessive alleles are not lethal in heterozygotes Will be passed on from generation to generation Only homozygous recessive individuals are affected.