Chapter 2 BIOLOGICAL BEGINNINGS © 2013 The McGraw-Hill Companies, Inc. All rights reserved.

The Role of Heredity on Development

Heredity One’s nature based on biological transmission of traits and characteristics Genetics Field within the science of biology that studies heredity Genetics Influence our Physical traits Behavioral traits Psychological problems HEREDITY AND GENETICS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. The nucleus of each human cell contains chromosomes Chromosomes: Threadlike structures made up of deoxyribonucleic acid, or DNA DNA: A complex molecule with a double helix shape; contains genetic information THE COLLABORATIVE GENE

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Genes: Units of hereditary information composed of DNA Genes direct cells to reproduce themselves and manufacture the proteins that maintain life Segments of DNA within chromosomes Regulate development of traits Transmitted by single gene or may be polygenic Approx. 20,500 genes in every cell (2008) Genome - The complete set of developmental instructions for creating proteins that initiate the making of a human organism THE COLLABORATIVE GENE

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE CELLS, CHROMOSOMES, DNA, AND GENES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Mitosis: Cellular reproduction in which the cell’s nucleus duplicates itself with two new cells being formed Strands of DNA break apart, duplicate and are rebuilt Each containing the same DNA as the parent cell, arranged in the same 23 pairs of chromosomes Cell division by which growth occurs Mutations can develop throughout our lives GENES AND CHROMOSOMES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Meiosis: A specialized form of cell division that occurs to form eggs and sperm (or gametes) 23 chromosome pairs divide Result is a new cell with only 23 chromosomes 22 pairs are autosomes 23rd pair are sex chromosomes GENES AND CHROMOSOMES

SOURCES OF VARIABILITY Meiosis Crossing Over

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Fertilization: A stage in reproduction whereby an egg and a sperm fuse to create a single cell, called a zygote Zygote: A single cell formed through fertilization FERTILIZATION

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Monozygotic Twins (MZ) Derived from a single zygote that has split in two Identical twins Dizygotic Twins (DZ) Derived from two zygotes Probability of twins increases Maternal age Use of fertility drugs SOURCES OF VARIABILITY

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE THE GENETIC DIFFERENCE BETWEEN MALES AND FEMALES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Mutation DNA - A mistake by cellular machinery, or damage from an environmental agent may produce a mutated gene, which is a permanently altered segment of DNA SOURCES OF VARIABILITY

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Genotype: A person’s genetic heritage; the actual genetic material Phenotype: The way an individual’s genotype is expressed in observed and measurable characteristics SOURCES OF VARIABILITY

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Dominant-Recessive genes principle Recessive gene is influential only if both genes are recessive Sex-Linked genes When a mutated gene is carried on the X chromosome, the result is called X-linked inheritance GENETIC PRINCIPLES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Genetic imprinting Occurs when genes have differing effects depending on whether they are inherited from the mother or the father Polygenetic inheritance Occurs when most characteristics are determined by the interaction of many different genes GENETIC PRINCIPLES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Traits are determined by pairs of genes Each member of pair is an allele Homozygous Both alleles for a trait are the same Heterozygous Alleles for a trait are different GENETIC PRINCIPLES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE HOW BROWN-HAIRED PARENTS CAN HAVE A BLOND-HAIRED CHILD

TRANSMISSION OF DOMINANT AND RECESSIVE TRAITS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE 2.5 – CHROMOSOMAL ABNORMALITIES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE SOME GENE-LINKED ABNORMALITIES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Ultrasound sonography – A prenatal medical procedure in which high frequency sound waves are directed into the pregnant woman’s abdomen PRENATAL DIAGNOSTIC TESTS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Amniocentesis Prenatal medical procedure in which a sample of amniotic fluid is withdrawn by syringe and tested for chromosomal or metabolic disorders PRENATAL DIAGNOSTIC TESTS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Chorionic villi sampling Prenatal medical procedure in which a small sample of the placenta is removed PRENATAL DIAGNOSTIC TESTS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Maternal blood or triple screening Identifies pregnancies that have an elevated risk for birth defects such as spina bifida and Down syndrome Noninvasive prenatal diagnosis (NIPD) Focuses on the isolation and examination of fetal cells circulating in the mother’s blood and analysis of cell- free fetal DNA in maternal plasma Fetal sex determination Noninvasive techniques have been able to determine the sex of the fetus at an earlier point by assessing cell-free DNA in maternal plasma PRENATAL DIAGNOSTIC TESTS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Infertility Inability to conceive after 12 months of regular intercourse without contraception In vitro fertilization (IVF) Eggs and a sperm are combined in a laboratory dish Adoption Social and legal process by which a parent-child relationship is established between persons unrelated at birth INFERTILITY AND REPRODUCTIVE TECHNOLOGY

CONCEPTION Against All Odds

FERTILIZATION Egg is viable for 24 hours Sperm is viable for 3 to 5 days “Unsafe period” is from day 9 to 15 if ovulation occurs on day 14 day 7 to 17 could be unsafe

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FEMALE REPRODUCTIVE ORGANS Figure 2.8

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. CONCEPTION 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

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Figure 2.9 CONCEPTION

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. CONCEPTION 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

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. The field that seeks to discover the influence of heredity and environment on individual differences in human traits and development Twin study: A study in which the behavioral similarity of identical twins is compared with the behavioral similarity of fraternal twins BEHAVIOR GENETICS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Adoption study: A study in which investigators seek to discover whether, in behavior and psychological characteristics, adopted children are more like their adoptive parents or more like their biological parents BEHAVIOR GENETICS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. FIGURE EXPLORING HEREDITY- ENVIRONMENT CORRELATIONS

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Shared environmental experiences: Siblings’ common experiences, such as their parents’ personalities and intellectual orientation, the family’s socioeconomic status, and the neighborhood in which they live Nonshared environmental experiences: The child’s own unique experiences, both within the family and outside the family, that are not shared by another sibling SHARED AND NONSHARED ENVIRONMENTAL EXPERIENCES

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. Epigenetic view: Emphasizes that development is the result of an ongoing, bidirectional interchange between heredity and environment Gene x Environment (G x E) interaction: The interaction of a specific measured variation in the DNA and a specific measured aspect of the environment THE EPIGENETIC VIEW AND GENE X ENVIRONMENT (G X E) INTERACTION

© 2013 The McGraw-Hill Companies, Inc. All rights reserved. The relative contributions of heredity and environment are not additive Complex behaviors have some genetic loading that gives people a propensity for a particular developmental trajectory CONCLUSIONS ABOUT HEREDITY- ENVIRONMENT INTERACTION