1. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Chapter 2 Heredity and Conception

2. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Your father determined whether you are female or male. Brown eyes are dominant over blue eyes. Heredity and Conception: Truth or Fiction?

3. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 You can carry the genes for a deadly illness and not become sick yourself. Identical twins are more likely than fraternal twins to share disorders such as schizophrenia and vulnerability to alcoholism. Heredity and Conception: Truth or Fiction?

4. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 120 to 150 boys are conceived for every 100 girls. Sperm travel about at random inside the woman’s reproductive tract, so that reaching the ovum is a matter of luck. Heredity and Conception: Truth or Fiction?

5. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Extensive athletic activity may contribute to infertility in the male. “Test-tube” babies are grown in a laboratory dish throughout their nine-month gestation period. Heredity and Conception: Truth or Fiction?

6. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 You can select the sex of your child. Heredity and Conception: Truth or Fiction?

7. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 The Influence of Heredity on Development The Nature of Nature

8. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Heredity –Defines one’s nature Genetics –Field within the science of biology that studies heredity Genetic influences –Physical traits –Behavioral traits –Psychological disorders What Is Meant by Heredity?

9. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Chromosomes –Found in cells –23 pairs of rod-like structures Genes –Segments within chromosomes –Regulate development of traits DNA –Large strands make up genes –Double spiral (helix) –Composed of phosphate (P), sugars (S), and base pairs What Are Chromosomes and Genes?

10. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Figure 2.1 Cells, Chromosomes, and DNA

11. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Mitosis –Cell division by which growth occurs –Strands of DNA break apart and are rebuilt –Result is identical copies of DNA strand What Happens During Cell Division?

12. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Figure 2.2 Mitosis

13. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Meiosis –Cell division by which sperm and ova are produced –23 chromosome pairs divide –Result is new cell with only 23 chromosomes 23 pairs are autosomes 23rd pair determines gender; X from mother and X or Y from father What Happens During Cell Division?

14. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Monozygotic Twins (MX) –Derived from a single zygote that has split in two –Genetically identical Dizygotic Twins (DZ) –Derived from two zygotes –Share 50% of genetic material How Are Twins Formed?

15. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Traits are determined by alleles –Pair of genes Homozygous –Alleles for a trait are the same Heterozygous –Alleles for a trait are different How Do Genes Determine Traits?

16. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Averaging –Effects of both alleles are shown –Incomplete dominance and codominance Law of Dominance –Dominant allele paired with recessive allele Dominant allele appears in child Dominant and Recessive Traits: Mendel’s Laws of Heredity

17. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Figure 2.4 Transmission of Dominant and Recessive Traits

18. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Table 2.1

19. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Cause: extra chromosome on 21st pair Probability increases with increased age of parent Characteristics of children –Facial features –Cognitive and physical deficiencies Adjustment of children Chromosomal Abnormalities: Down Syndrome

20. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Table 2.2

21. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Male with extra sex chromosome –XYY - extra Y chromosome –XXY - Klinefelter syndrome Female with abnormal number of sex chromosomes –X - Turner syndrome –XXX - Triple X syndrome Chromosomal Abnormalities: Sex Linked

22. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Recessive gene abnormalities –PKU (phenylketonuria) –Sickle-Cell Anemia –Tay-Sachs disease –Cystic Fibrosis Genetic Abnormalities

23. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Dominant gene abnormalities –Huntington’s disease Sex-linked abnormalities –Hemophilia –Duchenne muscular dystrophy Genetic Abnormalities

24. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Genetic Counseling –Addresses probability of genetic abnormalities Genetic Counseling and Prenatal Testing

25. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Amniocentesis –Routine among American women over age 35 –Used to detect over 100 chromosomal and genetic abnormalities –Indicates the sex of the baby –Some risk of miscarriage Genetic Counseling and Prenatal Testing

26. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Figure 2.6 Amniocentesis

27. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Chorionic Villus Sampling (CVS) –Can diagnosis abnormalities earlier than amniocentesis –Slightly greater risk of spontaneous abortion Ultrasound –Sonogram “picture” of fetus –Beneficial in determining position of fetus Blood Tests –Alpha-Fetoprotein (AFP) assay Genetic Counseling and Prenatal Testing

28. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Lessons in Observation: Prenatal Assessment

29. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 What is the most common chromosomal abnormality seen in live- born babies? Is an amniocentesis recommended for Eleanor? Why or why not? Lessons in Observation: Prenatal Assessment

30. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 According to the ultrasound results, what is the position of the baby? Describe the two structural abnormalities and/or marker of chromosomal abnormalities discussed as the ultrasound is performed. Lessons in Observation: Prenatal Assessment

31. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 What risks are associated with various prenatal assessment measures? How prevalent are birth defects resulting from genetic factors? Lessons in Observation: Prenatal Assessment

32. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 What are some other, non-genetic factors that can affect prenatal development? Eleanor took some careful planned actions (taking vitamins and eliminating alcohol consumption). What problems will this likely rule out? Lessons in Observation: Prenatal Assessment

33. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Heredity and the Environment Nature versus Nurture

34. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Genotypes –Set of traits inherited from parents Phenotypes –Actual sets of traits – product of genetics and environment What Is the Difference Between Our Genotypes and Our Phenotypes?

35. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Kinship studies –Genetic closeness of relatives Twin Studies –Monozygotic twins share 100% of genes –Dizygotic twins share 50% of genes (same as other siblings) –Reared together versus reared apart Adoption studies Using Research to Sort Out the Effects of Genetics and Environmental Influences on Development

36. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Conception Against All Odds

37. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Ova –Begin to mature at puberty –Monthly release of mature egg into Fallopian tube –Egg is propelled by cilia –If not fertilized, egg is discharged in the menstrual flow Conception: Against All Odds

38. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Sperm –Self propelled, and smaller than ova –Sperm with Y chromosome swim faster than sperm with X chromosome –From 200 to 400 million in ejaculate; only 1 in 1,000 arrive in vicinity of ovum –Sperm are attracted by chemical odor secreted by ova Conception: Against All Odds

39. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Figure 2.9 Female Reproductive Organs

40. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Only one sperm enters the zona pellucida –Sperm secrete enzyme hyaluronidase to allow penetration of the zona pellucida –When one sperm enters, the zona pellucida thickens, locking out other sperm Chromosomes from sperm and egg combine to form 23 new pairs What Process Brings Together the Genes From Each Parent?

41. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Major fertility problems among men –Low sperm count –Deformed sperm –Low sperm motility –Infections diseases –Direct trauma to testes Causes –Genetic factors, environmental poisons, diabetes, STI’s, overheating testes, pressure to testes, aging and effects of drugs Infertility and Other Ways of Becoming Parents: What Are the Causes of Infertility?

42. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Major fertility problems among women –Failure to ovulate Fertility drugs are used to cause women to ovulate –Infections Pelvic inflammatory disease (PID) –Endometriosis Obstruct Fallopian tubes –Barriers of disorders in passageways (i.e., Fallopian tubes) Infertility and Other Ways of Becoming Parents: What Are the Causes of Infertility?

43. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Artificial insemination –Sperm injected into mother’s uterus In Vitro Fertilization –Ova and sperm are fertilized, then implanted in mother’s uterus Donor IVF –Ovum harvested from donor woman; fertilized in vitro and implanted in recipient’s uterus Infertility and Other Ways of Becoming Parents: How Are Couples Helped to Have Children?

44. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Surrogate Mothers –Surrogate “substitutes” bring babies to term for another woman Adoption –Option chosen by singles and infertile couples Infertility and Other Ways of Becoming Parents

45. Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus Chapter 2 Cultural Folklore Sperm-Separation Procedures Preimplantation Genetic Diagnosis (PGD) Moral and Ethical Questions Selecting the Sex of Your Child