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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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Chapter 3 Review the following terms: phenotype genotype chromosome DNA gene mitosis meiosis gametes crossing over zygote monozygotic twins dizygotic twins. Chapter 3 Review the following terms: sex chromosomes dominant gene recessive gene pleiotropism modifier genes

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Presentation Transcript
slide1
Chapter 3

Review the following terms:

  • phenotype
  • genotype
  • chromosome
  • DNA
  • gene
  • mitosis
  • meiosis
  • gametes
  • crossing over
  • zygote
  • monozygotic twins
  • dizygotic twins
slide2
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
slide3
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?
pregnancy birth and lactation
PREGNANCY, BIRTH AND LACTATION

PREGNANCY:

Conception:

  • Three trimesters = nine months = prenatal period
    • Healthy vs. at risk pregnancies
    • Importance of intrauterine environment
slide5
Childbirth
  • Stages of childbirth
  • Normal vs. complicated childbirth, mismanagement.
  • Perinatal period:
    • from beginning of labour to 72 hrs. postpartum
  • Breastfeeding:
    • advantages for infant
pregnancy
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
slide7
Beginning of pregnancy
  • Implantation in the endometrium: @ 7 days approximately: blastocyst stage
  • Intrauterine environment very crucial. Critical and sensitive periods
  • Prenatal care essential
pregnancy8
PREGNANCY
  • Prenatal Care Essential:
    • Toxemia:
      • increased blood pressure
      • fluid retention
      • edema
      • can lead to eclampsia (fatal)
    • Gestational Diabetes
pregnancy9
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
pregnancy11
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
pregnancy12
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”)
pregnancy14
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
pregnancy17
PREGNANCY
  • TERATOGENS:
    • anything that causes birth defects (teratos = monster)
    • Critical vs. sensitive periods
    • Maternal Diseases:
      • Rubella
      • Toxoplasmosis (cat’s feces, raw meat)
      • CMV
      • AIDS
pregnancy19
PREGNANCY
  • TERATOGENS (Cont’d):
    • Radiation
    • Chemicals:
      • absorbed through lungs or skin
    • High Temperature:
      • hot bath
    • General Environmental Pollution:
      • what we eat, drink, breathe, touch
pregnancy20
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
pregnancy21
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
pregnancy22
Drugs:

prescription, e.g. DES, thalidomide

OTC

“recreational”, illegal

caffeine

aspirin, etc.

PREGNANCY
  • TERATOGENS (Cont’d):
pregnancy23
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
pregnancy24
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
pregnancy25
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
pregnancy26
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
pregnancy27
PREGNANCY
  • TERATOGENS (Cont’d):
    • Possible effects (cont’d):
      • organ malformation
      • sluggishness
      • future cancers
      • visual impairment
      • skeletal malformation
      • brain development
      • genital abnormalities
      • prematurity
pregnancy28
PREGNANCY
  • TERATOGENS (Cont’d):
    • Possible effects (cont’d):
      • respiratory difficulties
      • illnesses
      • microcephalia
      • heart defects
      • breach births (more C-sections)
pregnancy29
PREGNANCY
  • TERATOGENS (Cont’d):
  • THERE ARE NO TOTALLY SAFE DRUGS!
    • Most vulnerable:
      • brain, CNS
        • learning problems
        • ADHD
    • Most common mechanism:
      • oxygen deprivation
pregnancy31
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
pregnancy32
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
pregnancy33
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)
pregnancy34
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
low birth weight
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
types of low birth weight infants
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

causes of lbw
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)
risks for the lbw infant
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

intervention
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

slide40
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
the dutch hunger winter experience 1944
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
slide42
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
slide43
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!

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