Chapter 2- Genotype and Phenotype○ Genotype: an individuals unique genetic information○ Phenotype: an individual's directly observable characteristics - Genetic Foundations○ Chromosomes - store and transmit genetic information○ Genes - segments of DNA located along the chromosomes○ DNA - substances of which genes and chromosomes are made - Meiosis○ Process of cell division used to create gametes (sex cells)§ Halves the number of chromosomes normally present§ When the sperm and ovum unite, zygote will have 46 chromosomes again§ Ensures transmission of a constant quantity of genetic material - Terminology○ Autosomes: the 22 pairs of chromosomes that are not sex chromosomes○ Sex chromosomes: 23rd pair of chromosomes; determines sex; XX = female XY = male○ Gametes/sex cells: sperm and ova ○ Zygote: Sperm and ovum united - Twins○ Fraternal/Dizygotic - two zygotes or fertilized ova ○ Identical/Monozygotic - one zygote that divides into two individuals - Maternal Factors Related to Fraternal Twinning○ Ethnicity§ What country has the highest twin rate? - Benin§ Family history of twinning§ Age§ Nutrition§ Number of Births § Fertility drugs and In Vitro Fertilization- Patterns of Gene-Gene Interaction○ Alleles inherited from the parents that are either dominant or recessive, determining:§ Physical traits § Disabilities and diseases - Alleles○ Forms of the same gene on a pair of chromosomes:§ Appear at the same place on each chromosome in the pait§ One allele is inherited from each parent§ Homozygous: the two alleles are the same§ Heterozygous: the alleles differ- X-linked Inheritance○ A harmful allele is carried on the X chromosome○ Males are more likely to be affected§ Shorter Y chromosome lacks corresponding genes to override those on the X○ Nature compensates: Worldwide, about 106 boys are born for every 100 girls- Chromosomal AbnormalitiesChapter 2○ Down Syndrome - 95% of cases result from failure of 21st chromosome pair to separate during meiosis○ Sex Chromosome Abnormalities - problems with the X or Y chromosomes - Reproductive Choices○ Genetic counseling helps couples assess risks and family goals related to hereditary disorders ○ Options:§ Conception knowing risks§ Reproductive technologies§ Adoption- Prenatal Diagnostic Methods○ Amniocentesis (most widely used)○ Chorionic Villus Sampling○ Fetoscopy○ Ultrasound○ Maternal Blood Analysis○ Preimplantation Genetic Diagnosis - Reproductive Technologies○ Donor insemination and in vitro fertilization○ Surrogate motherhood○ New frontiers in reproductive technology§ Ethical concerns?§ Preimplantation genetic diagnosis- Discussion Questions ○ What about disorders for which no preventative measures or treatments are available?○ What happens when a young adult is found to have the mutation that causes a fatal disorder?○ Would such a person still be able to buy insurance or get the job promotion he or she applied for?○ How would this information affect his or her family and social life?- Genetic Engineering ○ Human Genome Project§ Researchers have mapped the sequence of all human DNA base pairs§ Working on identifying all genes and their functions in order to understand human disorders§ Thousands of genes already identified including those involved in cystic fibrosis. Duchenne muscular dystrophy. Huntington disease and many forms of cancer○ New treatments under development include gene therapy and proteomics - Environmental Contexts for Development○ Family○ Socioeconomic status○ Poverty/affluence ○ Neighborhoods○ Schools○ Cultural context - Socioeconomic Status (SES)○ Index that combines three related variables§ Years of educationChapter 2§ Prestige of one's jobs and skill it requires§ Income§ First two measures social status; the last measure economic status ○ Sociostatus and family functioning§ SES is linked to:□ Timing of marriage and parenthood□ Family size□ Child-rearing values and expectations□ Communication and discipline styles □ Parents' education and economic security□ Children's cognitive and social development ○ Poverty§ 21% of US children live in poverty□ Rates higher for children of parents under age 25, ethnic minorities and single mothers§ Risks of poverty:□ Lifelong poor physical health□ Poor cognitive development and academic achievement □ Mental illness□ Impulsivity, aggression and antisocial behavior □ Hostile family interactions ○ Affluence§ Risks of affluence:□ Poor academic achievement□ Alcohol and drug use □ Delinquency□ Anxiety and depression§ Unavailable parents:□ Lack emotional closeness and supervision□ Make excessive demands for