Biological and Environmental Factors Chapter 2 Summary Notes * Notes for educational purposes only-use with course textbook

Overview Bases for Genetic make-up Choices in Reproduction Development and the Family The Relationship Between Heredity and Environment

Genetics Heredity and environment are foundations of development Genotype- genetic make-up Phenotype- observable characteristics

Genetic Code Body composed of over a trillion cells Center of cell is nucleus which contains chromosomes Chromosomes- store and transmit genetic information DNA- double strain molecules that makeup chromosomes and contain genetic code Gene- segment of DNA molecule Mitosis- cell duplication (each cell receives exact copy of genetic code)

Sex Cells Gametes-sex cells (sperm 23 chromosomes and ovum 23 chromosomes) Meiosis- cell division that forms gametes No two gametes will ever be the same Zygote- sperm and ovum unite at conception 46 Chromosomes Sperm are produced continuously; all ova are present at birth 22 autosomes; 1 sex chromosome; xy- male; xx- female

Mulitiple Births Twins –Fraternal (dizygotic) most common type Two ova are fertilized; genetic makeup similar to ordinary siblings –Identical (monozygotic) one zygote separates into two clusters of cells that become two individuals; same genetic makeup Triplets (3); Quadurplets (4); Quintuplets (5); Sextuplets (6), Septuplets (7)

Increase in Multiple Births?!

Increase Facts % single births; 33% twin births; 101% triplets and higher Trends in family planning and advances in reproductive technology assist in increase

Patterns of Genetic Inheritance 2 forms of genes occur at the same place on the autosome- father & mother Homozygous- alike genes from both parents (inherited trait) Heterozygous- different genes from both parents- relationship of genes determine trait that will appear. Dominant- recessive inheritance- a pattern one gene’s influence is exhibited (heterozygous)

Dominant- Recessive Terms Dominant- expressed gene Recessive- not expressed Carrier- heterzygous; pass recessive gene to his/her children

Diseases that are result of recessive genes PKU Cystic Fibrosis Sickle Cell Anemia Tay-Sachs disease Hemophilia (Page 50 in text)

Who is more at risk ( Multiple Births)? Older women Women with more children Fertility drug clients African American Women (fraternal twins) Tall, normal, or overweight (fraternal twins)

Patterns of Genetic Inheritance 2 forms of each gene occur at the same place on the autosomes- 1 mother; 1 father Homozygous- both genes are alike Heterozygous- relationship between genes determine trait that will appear

Dominant- Recessive Inheritance A pattern in a heterozygous relationship only one gene’s influence is exhibited Dominant- expressed Recessive- not expressed Carrier- heterozygous relationship passes recessive gene

Diseases with recessive trait PKU Sickle Cell Anemia Tay-Sachs Disease Cystic Fibrosis Cooley’s Anemia (Pages in text) Genetically linked illnesses

Codominance –Both genes influence the person’s charateristics –Sickle Cell Anemia

Mutation Change in DNA segment Harmful genes By chance Or by hazardous substances in the environment

X-linked inheritance- recessive gene is carried on the X-Chromosome –Males more likely to be affected (sex chromosomes don’t match) –Hemophilia Males may be at a disadvantage in other areas not necessary linked to X-linked inheritance- miscarriage and infant deaths Learning disability, behavior disorders mental retardation (Halpern, 1997)

Genetic Imprinting Pattern of inheritance where some genes are chemically marked in such a way that one pair is activated regardless of its makeup –Diabetes in the father –Asthma in the mother –Fragile X syndrome (MR, autism) mother

Chromosomal Abnormalities Defect occurs during meiosis (DNA) Down Syndrome –21 st chromosome contains extra genetic material –Physical features- short, stocky build, flatten face, protruding tongue, almond shape eyes, possible heart and intestinal defects, speech problems, delayed motor and cognitive defects –Increase chances of having a baby with Down Syndrome with age of mother

Abnormalities in Sex Chromosomes Either the presence of extra chromosome or the lack of one of the X chromosomes Triple X syndrome (XXX)- girl- verbal difficulties Turner syndrome- (XO) missing X-spatial relationships Klinefelter syndrome (XXY)- verbal difficulties

Reproductive Choices Genetic Counseling- communication about chances of couples having a baby with hereditary disorders Prenatal diagnostic methods –Page 55 in text

Other choices Adoption In vitro fertilization Fertility drugs

Environmental Factors Family Friends School Experiences Society Culture

Social Systems Perspective Family as complex system –Behavior of family affects those of other family members Influence is directed or indirect- third party can support or undermine other family relationships Family dynamic ever- changing system Can be modified by important life events Development status of each family member and historical time period effects families

Socioeconomic Status (SES) and Family Functioning 3 variables –Years of education –Job prestige and skills required –Income –SES may affect differences in child-rearing practices –Lower- SES family may focus on external characteristics (obedience, neatness, cleanliness) –Higher SES focus on psychological traits-curiosity Happiness, and self- direction As early as 2 nd year of life SES affects with cognitive and language development

Impact of Poverty 36 million people 14% of the population Hardest hit –Parents under 25 with young children –Elderly who live alone –Ethnic minorities –Women –20% children; 32% Hispanic; 40% African American; 32% Native American

More on Poverty Parents in poverty –Experience hassles and crises affecting child- rearing ability –Poor housing and dangerous neighborhoods increase stress levels of poor families –Homeless children suffer from developmental delays, emotional stress, health problems, school absenteeism, poor academic performance

Beyond the Family Community impact on family –Child abuse and neglect are greatest With weak family and community ties Family stress and child adjustment problems are reduced with strong family ties Safe neighborhoods and communities with physical and social support Influence well-being in adulthood Smaller towns- fewer culture experiences than cities- greater community involvement and safer environments

Culture Cultures shape family interactions and community settings beyond the home American cultural values- independence –Self-reliance, privacy –Subcultures- groups of people with beliefs and customs that differ from those of the larger culture

African American Extended Family Extended family- 3 or more generations live together Survival poverty, prejudice and economic deprivation (McAdoo) More kin visits Reduce stress Grandmothers are significant Elderly have higher life satisfaction Strong Family bonds, child development Survival for future generations

Individualism vs. Collectivism Individualism societies- people think of themselves as separate entities; concerned with their own goals (US) Collectivism societies- people define themselves as part of a group and stress group over individual goals