Chapter 3
1 / 43

chapter 3review the following terms:phenotypegenotypechromosomednagenemitosismeiosisgametescrossing overzygotemonozygoti - PowerPoint PPT Presentation

  • Uploaded on

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

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'chapter 3review the following terms:phenotypegenotypechromosomednagenemitosismeiosisgametescrossing overzygotemonozygoti' - Anita

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Slide1 l.jpg

Chapter 3

Review the following terms:

  • phenotype

  • genotype

  • chromosome

  • DNA

  • gene

  • mitosis

  • meiosis

  • gametes

  • crossing over

  • zygote

  • monozygotic twins

  • dizygotic twins

Slide2 l.jpg

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 l.jpg

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 l.jpg



  • Three trimesters = nine months = prenatal period

    • Healthy vs. at risk pregnancies

    • Importance of intrauterine environment

Slide5 l.jpg


  • Stages of childbirth

  • Normal vs. complicated childbirth, mismanagement.

  • Perinatal period:

    • from beginning of labour to 72 hrs. postpartum

  • Breastfeeding:

    • advantages for infant

Pregnancy l.jpg

  • 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 l.jpg

Beginning of pregnancy

  • Implantation in the endometrium: @ 7 days approximately: blastocyst stage

  • Intrauterine environment very crucial. Critical and sensitive periods

  • Prenatal care essential

Pregnancy8 l.jpg

  • Prenatal Care Essential:

    • Toxemia:

      • increased blood pressure

      • fluid retention

      • edema

      • can lead to eclampsia (fatal)

    • Gestational Diabetes

Pregnancy9 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg


    • anything that causes birth defects (teratos = monster)

    • Critical vs. sensitive periods

    • Maternal Diseases:

      • Rubella

      • Toxoplasmosis (cat’s feces, raw meat)

      • CMV

      • AIDS

Pregnancy19 l.jpg

  • TERATOGENS (Cont’d):

    • Radiation

    • Chemicals:

      • absorbed through lungs or skin

    • High Temperature:

      • hot bath

    • General Environmental Pollution:

      • what we eat, drink, breathe, touch

Pregnancy20 l.jpg

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 l.jpg

  • 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 l.jpg


prescription, e.g. DES, thalidomide


“recreational”, illegal


aspirin, etc.


  • TERATOGENS (Cont’d):

Pregnancy23 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • TERATOGENS (Cont’d):

    • Possible effects (cont’d):

      • organ malformation

      • sluggishness

      • future cancers

      • visual impairment

      • skeletal malformation

      • brain development

      • genital abnormalities

      • prematurity

Pregnancy28 l.jpg

  • TERATOGENS (Cont’d):

    • Possible effects (cont’d):

      • respiratory difficulties

      • illnesses

      • microcephalia

      • heart defects

      • breach births (more C-sections)

Pregnancy29 l.jpg

  • TERATOGENS (Cont’d):


    • Most vulnerable:

      • brain, CNS

        • learning problems

        • ADHD

    • Most common mechanism:

      • oxygen deprivation

Pregnancy31 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg

  • 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 l.jpg
Low Birth Weight


  • 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 l.jpg
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)


  • 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 l.jpg
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 l.jpg
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 l.jpg

  • 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


Slide40 l.jpg

  • 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 l.jpg
The Dutch Hunger Winter Experience (1944) how environmental factors (diet, stress, etc.) can change gene function without altering the DNA sequence

  • 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 l.jpg

In adulthood: how environmental factors (diet, stress, etc.) can change gene function without altering the DNA sequence

  • 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 l.jpg

Maternal Influences in Utero how environmental factors (diet, stress, etc.) can change gene function without altering the DNA sequence

  • 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