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Chapter 3 Review the following terms: phenotype genotype chromosome DNA gene mitosis meiosis gametes crossing over zygot PowerPoint Presentation
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Chapter 3 Review the following terms: phenotype genotype chromosome DNA gene mitosis meiosis gametes crossing over zygot

Chapter 3 Review the following terms: phenotype genotype chromosome DNA gene mitosis meiosis gametes crossing over zygot

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Chapter 3 Review the following terms: phenotype genotype chromosome DNA gene mitosis meiosis gametes crossing over zygot

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  1. Chapter 3 Review the following terms: • phenotype • genotype • chromosome • DNA • gene • mitosis • meiosis • gametes • crossing over • zygote • monozygotic twins • dizygotic twins

  2. Chapter 3 Review the following terms: • sex chromosomes • dominant gene • recessive gene • pleiotropism • modifier genes • PKU as example of autosomal disease (p. 78) • X-linked inheritance • mutation • polygenic • Down syndrome • disorders of the sex chromosomes (p. 83) • genetic counseling

  3. Ethical question: • We can now treat PKU through diet, so children who would have died in the first year of life can live normal life spans • When they reproduce, they will pass on their genetic disease to their offspring • What will happen to the population over time?

  4. PREGNANCY, BIRTH AND LACTATION PREGNANCY: Conception: • Three trimesters = nine months = prenatal period • Healthy vs. at risk pregnancies • Importance of intrauterine environment

  5. Childbirth • Stages of childbirth • Normal vs. complicated childbirth, mismanagement. • Perinatal period: • from beginning of labour to 72 hrs. postpartum • Breastfeeding: • advantages for infant

  6. PREGNANCY • Only a few hundred sperm arrive where egg is, in the Fallopian tube, and surround ovum. • Only one (usually) penetrates ovum • Stages of uterine development: • zygote: • 1-14 days • embryo: • 3-8 weeks • fetus: • 9-40 weeks

  7. Beginning of pregnancy • Implantation in the endometrium: @ 7 days approximately: blastocyst stage • Intrauterine environment very crucial. Critical and sensitive periods • Prenatal care essential

  8. PREGNANCY • Prenatal Care Essential: • Toxemia: • increased blood pressure • fluid retention • edema • can lead to eclampsia (fatal) • Gestational Diabetes

  9. PREGNANCY • Natural method of conception can fail • Most common reason: • STDs in both men and women, which lead to infertility (e.g. blocked Fallopian tubes or vas deferens) • Reproductive technology can help infertile couples • Most recent dramatic technology: • cloning

  10. PREGNANCY • More Established Reproductive Technologies: • Artificial Insemination: • Introducing sperm into woman’s vagina or uterus by artificial means • single woman • husband low sperm count • husband dead • husband infertile: donor sperm

  11. PREGNANCY • More Established Reproductive Technologies (Cont’d): • IVF: in vitro fertilization: • test tube or Petri dish is used to mix gametes; once dividing, surgically implanted into woman’s uterus • can use both parents’ gametes • one parent plus donor’s • can be implanted in surrogate’s uterus (“rent-a-womb”)

  12. PREGNANCY • Testing the Conceptus for Abnormalities: • amniocentesis (11-14 weeks) • CVS: chorionic villus sampling (villi) (6-8 weeks) • ultrasound (12-16 weeks) • fetoscopy • blood test

  13. PREGNANCY • TERATOGENS: • anything that causes birth defects (teratos = monster) • Critical vs. sensitive periods • Maternal Diseases: • Rubella • Toxoplasmosis (cat’s feces, raw meat) • CMV • AIDS

  14. PREGNANCY • TERATOGENS (Cont’d): • Radiation • Chemicals: • absorbed through lungs or skin • High Temperature: • hot bath • General Environmental Pollution: • what we eat, drink, breathe, touch

  15. PREGNANCY e.g. phthalates: • alter boys’ genitals • hypospadias: urethral opening in wrong spot: along the shaft, even scrotum • increase in cryptorchidia: undescended testes (more cancer risk) • damage to Sertoli cells: decreased sperm production; decreased quality

  16. PREGNANCY • increased allergies • premature breast development in girls • found in: • perfumes • nail polish • flooring • soft plastics • paints • adhesives • IV lines, medical tubes e.g. nasogastric tube

  17. Drugs: prescription, e.g. DES, thalidomide OTC “recreational”, illegal caffeine aspirin, etc. PREGNANCY • TERATOGENS (Cont’d):

  18. PREGNANCY • TERATOGENS (Cont’d): • Smoking: • nicotine • CO: • 200 times more affinity to Hgb than oxygen • oxygen supply compromised (5% less) • decreases sperm motility: • lower fertility • less progesterone: • miscarriages • placental problems • higher morbidity and mortality • from 9/1000 to 33/1000 • higher rates of cleft palate and hare lip

  19. PREGNANCY • TERATOGENS (Cont’d): • Alcohol: • FASD (fetal alcohol spectrum disorder) • brain abnormalities: • learning difficulties • ADDH • mental retardation, etc. • possible damage to eyes, ears, immune system, internal organs, joints, limbs • low birth weight • increased prematurity, miscarriage and stillbirth risk

  20. PREGNANCY • TERATOGENS (Cont’d): • Alcohol: • FASD (fetal alcohol spectrum disorder) (Cont’d) • growth retardation • facial and cranial malformations • dose and timing related • no safe dose • there is no cure for FASD • leading cause of preventable mental retardation

  21. PREGNANCY • TERATOGENS (Cont’d): All drug effects: • Dose Related: • Interactions: hard to tell main effects • Possible effects: • miscarriage • stillbirth • low birth weight • irritability, hard to soothe • shorter attention span (learning) • tremors • digestive difficulties

  22. PREGNANCY • TERATOGENS (Cont’d): • Possible effects (cont’d): • organ malformation • sluggishness • future cancers • visual impairment • skeletal malformation • brain development • genital abnormalities • prematurity

  23. PREGNANCY • TERATOGENS (Cont’d): • Possible effects (cont’d): • respiratory difficulties • illnesses • microcephalia • heart defects • breach births (more C-sections)

  24. PREGNANCY • TERATOGENS (Cont’d): • THERE ARE NO TOTALLY SAFE DRUGS! • Most vulnerable: • brain, CNS • learning problems • ADHD • Most common mechanism: • oxygen deprivation

  25. PREGNANCY • TERATOGENS (Cont’d): • Maternal stress: • acute or chronic (worse) • adrenaline, corticosteroids: • compromise oxygen supply for infant • after birth: • digestive problems • low birth weight • irritability

  26. PREGNANCY • TERATOGENS (Cont’d): • Maternal age: • no more obstetrical complications (if healthy) • increased Down’s syndrome • Other effects of these variables: • affect maternal-infant interaction • abuse • neglect • rejection

  27. PREGNANCY • Maternal Nutrition: • First trimester: • usually not an issue – special cases • Second trimester: • quality • Third trimester: • quality and quantity • Important: • Folic acid: prevents neural tube defects (eg. spina bifida)

  28. PREGNANCY • Maternal Nutrition (Cont’d): • Infant Optimal Weight: • 7½ - 8 lbs. (European stock) • Low Birth Weight: • 5½ lbs. or 2,500 g • Montreal Diet Dispensary, Agnes Higgins: • 500 extra daily calories: • 1 qt. milk • 1 egg • 1 orange

  29. Low Birth Weight Definition • Low Birth Weight: • Infant weighs less than 5.5 pounds (2500 g) • Premature: • Infant is born at less than 38 weeks gestation

  30. Types of Low Birth Weight Infants *Low birth weight infants are either: • Preterm (born at less than 38 weeks gestation) • Small for gestational age (may be born at term) OR • Preterm & small for gestational age *5.8% of births in Canada involve LBW infants (1996) *LWB births involve more risk than “normal” births

  31. Causes of LBW • There is no one cause for LBW, but some include: • maternal smoking; drinking; drugs • maternal diabetes • lack of adequate prenatal care • poor nutrition • infection • unknown causes • Even healthy mothers with good prenatal care may give birth to a LBW infant (placental problems)

  32. Risks for the LBW Infant • Health • heart & lung • vision • hearing • motor problems • developmental problems • Environmental • abuse • attachment problems • Later Deficits • learning difficulties • health problems may persist into adulthood There is no way to predict which problems, if any an infant may have

  33. Intervention • Necessary at birth (resuscitation, drugs, month + hospital stay) • Various tests (vision, hearing, developmental) help detect problems • Research here at MUN involves assessing LBW infants *Note that intervention does not always lead to a successful outcome; all infants are different

  34. Maternal diet can affect the genes: epigenetics research: how environmental factors (diet, stress, etc.) can change gene function without altering the DNA sequence • Genes can predispose toward cancer or diabetes or schizophrenia, but prenatal environment can override this • Genes can be turned “on” or “off”, be intensified or dimmed

  35. The Dutch Hunger Winter Experience (1944) • 40,000 pregnant women affected • 400 calories a day • Babies in third trimester gestation (born right after Allied liberation): low birth weight (average 8 oz. less), shorter, smaller head circumference • Babies born 3 months after liberation: normal weight • Babies conceived 3 months before liberation (first trimester): stillbirth rate doubled • Both second and third trimester babies: higher death rate in the first week post-partum

  36. In adulthood: • First trimester (conceived 3 months before liberation): twice the rate of CNS defects, i.e. spina bifida and hydrocephalus. Lack of folic acid Effects on third generation: • Women who were 1st and 2nd trimester babies during the famine had underweight babies despite good nutrition and health

  37. Maternal Influences in Utero • Undernutrition: fetus will divert nutrients (blood) to its brain, shortchanging other organs • Liver growth can be stunted: high cholesterol in adulthood • Also, obesity is more likely in adulthood: appestat programmed to overeat? • Maternal stress: cortisol. Fetus has a “counterhormone” that fails if mom undernourished • Maternal diabetes: fetus gets high levels of glucose, stress to fetal pancreas leads to diabetes later in life • Maternal estrogen: in high levels can lead to breast cancer. Correlated with too high birth weight • Low birth weight: prone to heart disease later. Risk of hypertension INTRAUTERINE ENVIRONMENT IS EXTREMELY IMPORTANT!