1. Hereditary Influences on Development Chapter 3

3. The Genetic Code Chromosomes Chromosomes –Rodlike –Store and transmit genetic information –Matching pairs –46 chromosomes, 23 pairs… Comprised of deoxyribonucleic acid, DNA Comprised of deoxyribonucleic acid, DNA

6. Gametes/Sex Cells Sperm, ovum Sperm, ovum Contain only 23 chromosomes Contain only 23 chromosomes Formed through meiosis Formed through meiosis “Regular” body cells  mitosis “Regular” body cells  mitosis Sex cells  meiosis Sex cells  meiosis Crossing over Crossing over

8. Multiple Offspring Identical/monozygotic twins Identical/monozygotic twins Fraternal/dizygotic twins Fraternal/dizygotic twins

10. Patterns of Genetic Influence Phenotype Phenotype Genotype Genotype Can have same phenotype but different genotypes…why? Can have same phenotype but different genotypes…why?

11. How Are Genes Expressed? Simple dominant-recessive inheritance Simple dominant-recessive inheritance –Each different form of a gene is called an allele –Alleles alike = homozygous Alleles different = heterozygous

12. How Are Genes Expressed? Dominant-recessive Dominant-recessive

14. Examples of Dominant-Recessive Genes Dominant TraitsRecessive Traits Eye colorbrown eyesgrey, green, hazel, blue Visionfarsightednessnormal vision normal visionnearsightedness normal visionnight blindness normal visioncolor blindness* Hairdark hairblonde, light, red hair non-red hairred hair curly hairstraight hair full head of hairbaldness* widow’s peaknormal hairline *sex-linked characteristic

15. Examples of Dominant-Recessive Genes Dominant Traits Recessive Traits Facial featuresdimplesno dimples unattached earlobesattached earlobes frecklesno freckles broad lipsthin lips Appendagesextra digitsnormal number fused digitsnormal digits short digitsnormal digits fingers lack 1 jointnormal joints limb dwarfingnormal proportion clubbed thumbnormal thumb double-jointednessnormal joints

16. Examples of Dominant-Recessive Genes Dominant Traits Recessive Traits Other immunity to poison ivy susceptibility to poison ivy normal pigmented skin albinism normal blood clotting hemophilia* normal hearing congenital deafness normal hearing and speaking deaf mutism normal – no PKU phenylketonuria (PKU) *sex-linked characteristic

17. How Are Genes Expressed? If heterozygous, can pass on a recessive allele to children If heterozygous, can pass on a recessive allele to children –Carriers Phenylketonuria (PKU) Phenylketonuria (PKU)

18. How Are Genes Expressed? Sex-linked inheritance Sex-linked inheritance Codominance Codominance Polygenic inheritance Polygenic inheritance

19. Hereditary Disorders Chromosomal abnormalities Chromosomal abnormalities

21. Hereditary Disorders Autosomal abnormalities Autosomal abnormalities –Most frequent is Down syndrome (trisomy 21) –Mental retardation –Distinctive physical features Mutations Mutations

22. Detecting Hereditary Disorders Amniocentesis Amniocentesis Chorionic villus sampling Chorionic villus sampling Ultrasound Ultrasound Know the procedures, advantages, and disadvantages of each… Know the procedures, advantages, and disadvantages of each…

23. Genetic-Environmental Interactions Reaction range Reaction range

24. Range of Reaction

25. Canalization Heredity restricts development of some characteristics Heredity restricts development of some characteristics Examples = babbling, motor development Examples = babbling, motor development

26. Behavioral Genetics The scientific study of how genotype interacts with the environment to determine behavioral attributes such as intelligence, personality, and mental health The scientific study of how genotype interacts with the environment to determine behavioral attributes such as intelligence, personality, and mental health Methods of studying hereditary influences Methods of studying hereditary influences –Selective breeding –Family studies  Twin studies  Adoption studies

27. Behavioral Genetics Twin studies Twin studies –Identical/fraternal reared together –Adoption studies –Identical twins reared apart Calculate concordance rates Calculate concordance rates Heritability coefficient Heritability coefficient

28. Behavioral Genetics Heritability coefficient (H) = (r identical – r fraternal) X 2 Heritability coefficient (H) = (r identical – r fraternal) X 2 Environmental influences Environmental influences –Nonshared environmental influences (NSE)  1 – r identical twins reared together –Shared environment influences  1 - (H + NSE)

29. Behavioral Genetics Anxiety scale score Anxiety scale score –Monozygotic twins: r =.78 –Dizygotic twins: r =.51 –Heritability:  2(.78-.51)  2(.27) .54 –Nonshared:  1 -.78 =.22 –Shared:  1 – (.54 +.22)  1 -.76 =.24

30. Behavioral Genetics Favorite color Favorite color –Monozygotic twins: r =.26 –Dizygotic twins: r =.23 –Heritability:  2(.26-.23)  2(.03) .06 –Nonshared:  1 -.26 =.74 –Shared:  1 – (.06 +.74)  1 -.80 =.20

31. Molecular Genetics To discover the precise locations of genes that determine an individual’s susceptibility to various diseases and other aspects of health and well-being To discover the precise locations of genes that determine an individual’s susceptibility to various diseases and other aspects of health and well-being Genome = complete set of instructions for making an organism Genome = complete set of instructions for making an organism Human Genome Project Human Genome Project