1. Development Meiosis: “reduction division”; variety Spermatogenesis (tubules):  1 immature sperm (46) 4 mature sperm (23)  Begins at puberty Oogenesis (ovaries):  1 immature egg (46) 1 mature egg (23)  Arrested at prophase I (begins again at puberty

2. Fetal Development 3 rd Week: primitive streak at back of embryo notochord Neural Tube brain and spinal cord 4 th Week: arms and legs; blood cells; lungs and kidneys Heart beats at day 18 5 th /6 th Weeks: large head; eyes open (no lids); apoptosis for fingers and toes 8 th Week: “fetus” 3 rd /4 th Months: kicking; beginning of teeth; vocal cords form; breathing of amniotic fluid in and out Digestive/Respiratory systems mature last Critical Period: time when genetic abnormalities, toxic substances or viruses can alter a specific structure

3. Teratogens: chemicals or other agents that cause birth defects Thalidomide (1957-1961) affected 10,000 European babies; used to alleviate morning sickness incomplete or missing limbs Cocaine: can cause spontaneous abortion by inducing a stroke in the fetus Cigarettes: can cause spontaneous abortions, stillbirths, prematurity, low birth rates; CO crosses placenta (affects hemoglobin of fetus) Alcohol: Fetal Alcohol Syndrome small head, flat nose and face; intelligence impairment; slow growth; lack verbal and social skills

4. Nutrients: Vitamin A derivatives (Accutane): can cause spontaneous abortion, heart and NS defects; Vitamin C abnormalities: bruising, scurvy; Malnutrition: spontaneous abortion, short stature, tooth decay Occupational Hazards Viral Infection: Herpes simplex: skin sores, NS problems; HIV: higher risk for low birth weight, prematurity, stillbirths; Hepatitis B: liver problems as adults; Rubella (German measles): heart defects, cataracts, learning problems Maturation and Aging: Age 30: turning point for decline Alzheimer Disease: 5-10% inherited; symptoms in 40’s, 50’s; protein deposits in memory centers  Tau (protein): disrupts microtubules in nerve cells (destroying cell shape)

5. Accelerated Aging Disorders: Segmental Progeroid Syndromes: cells’ inability to adequately repair DNA (mutations accumulate) Longevity: Aging: result of genetic activity and lifetime of environmental influences Chromosome #4: gene variants associated with a long life Adoption Studies: effects of genes vs. environmental influences