Genetics, Conception & Prenatal Module 3
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Children
Genetics, Conception & Prenatal
Module 3
1
3.1Genetic Foundations
Genetic Foundations We carry a genetic code Inherited from parents Fertilized human eggCarries human codeBegin life as a single cellContains our entire genetic code
(Human egg about to pop)
ChromosomesNucleus of each human cell containsChromosomesThread-like structures made up of deoxyribonucleic acid, or DNA DNAComplex molecule that has a double helix shape & contains genetic informationUnique to all (except identical twins)Same genetic code
GenesGenesUnits of hereditary information composed of DNA. Short segments of DNADirect cells to reproduce themselvesManufacture proteins that maintain life Blueprint for cell reproduction
Human Genome Project 2003 GenomeComplete genetic information (DNA) of an organism Preliminary map of human genome Complete set of developmental instructions for creating proteins that initiate making of a human organismHumans about 30,000 genes
Genetic ExpressionGenetic expression affected by their environmental conditionsHormones in blood stream Turn genes on/offHormones affected by environmental conditions such asLightDay lengthNutritionBehavior
Genetic ExpressionNumerous studies showExternal events outside Original cellPerson+Events inside cellCan excite or inhibit gene expressionStressHormone: cortisol 5 fold increase in DNA damageWoman who is pregnant , 4 yr old son missing
Genetic PrinciplesDominant-Recessive Genes PrincipleRecessive gene is influential only if both genes are recessive1 gene of a pair always exerts its effects examples: hair coloreyesightfreckles
Genetic Foundations
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Dominant-Recessive Genes Principle Dominant1 gene of pair always exerts its effects Recessive geneExerts influence only if 2 genes of a pair are both recessive may be overridden by dominant genemay be carried from generation to generation but not expressed in phenotypeRed hair
Genotype & PhenotypeGenotypeAll of a persons genetic material
Genotype & PhenotypePhenotype Observable characteristics Phenotypes include Physical characteristicsHeightWeightHair color Psychological characteristicsPersonalityIntelligence
Genetic PrinciplesWhat determines how a genotype is expressed to create a particular phenotype?Ex: Look exactly like sister/brother?Same geneticsWhy not?Science not totally sure
3.2Genetic Abnormalities
Genetic PrinciplesSex-Linked Genes: X-linked inheritanceMutated gene carried on X chromosomeMales have only 1 X chromosomeMore vulnerable to X-linked disorders HemophiliaFragile-X syndrome
Sex-Linked Chromosome Abnormalities
Sex-Linked XX or XYChromosome AbnormalitiesKlinefelter syndromeDisorder in males; extra X chromosomeFragile X syndromeAbnormality in X chromosome;becomes constricted or breaksTurner syndromeFemale disorder; X chromosomemissing or partially deletedXYY syndromeDisorder in males; extra Y chromosome
Genetic Foundations
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Conception and Pregnancy3.3
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FROM FERTILIZATION TO EMBRYO Here is an interactive site you might find helpful.The Brain From Top to Bottomhttp://thebrain.mcgill.ca/flash/d/d_09/d_09_cr/d_09_cr_dev/d_09_cr_dev.html
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1.V. The Moment of Conception
http://www.youtube.com/watch?v=mdGsLRGBsCU
2. V. Human DevelopmentHuman Developmenthttp://www.youtube.com/watch?v=UgT5rUQ9EmQ&feature=PlayList&p=2E2643C1A6F72FBA&index=1
Conception & Period of the ZygoteZygoteEgg & a sperm fuseCreate single cell23 unpaired chromosomes from egg & sperm combine to form 1 set of 23 paired chromosomes1 chromosome of each pair is fromMothers eggFathers sperm Each parent contributes 1/2 of offsprings genetic material
PrenatalDevelopment
3 prenatal periods1. Germinal Period (period of the zygote)2. Embryonic Period3. Fetal Period
(Gabby Eats Frogs)
1.The Germinal PeriodTakes place in 1st 2 weeks after conception. 1. Creation of zygote 2. Cell division3. Attachment of zygote to uterine wall
The Course of Prenatal Development
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The Germinal PeriodEgg goes from ovary through fallopian tube (uterine tube)
Creation of zygote (fertilized egg) Mature human egg23 chromosomesMature human sperm23 chromosomesEgg fertilized by spermCreates zygote46 chromosomes
The Germinal Period
Many sperm race to egg1 winsusually.Makes way to egg by smellIncluding other mechanismsOnce a sperm penetratesChemical is releasedPrevents other sperm from entering
The Germinal Period
The Germinal Period
Two sperm fertilize ovum?Usually miscarriage1% twins (real case)1st twin Hermaphrodite5% XY, 95% XX2nd twinMale, has 50% XX and 50% XY.
Zygote
The Germinal Period
2. The Embryonic Period
2. The Embryonic PeriodOccurs 2 - 8 weeksafter conceptionCell differentiation intensifiesSupport systems for cells formOrgans appearHeart first The Course of Prenatal Development
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The Placenta and the Umbilical CordFig. 3.2
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PlacentaAttaches to inside of uterus Connected to fetus by umbilical cordProduces pregnancy-related hormonesSmall blood vessels carrying fetal blood run through placenta, which is full of maternal blood.
Embryos Life-Support SystemPlacenta Intertwines Does not join mother & babyUmbilical cordConnects baby to placenta
The Course of Prenatal Development
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Amnion & amniotic fluidProvides babys environmentDrinks itOrganogenesisOrgan formationEspecially vulnerable to environmental changes
Embryos Life-Support System
3. The Fetal PeriodBegins 2 mos after conceptionLasts @ 7 mos - birthLargest prenatal size & weight gainsDevelopment:FingerstoeslungsSkin featuresreflexesThe Course of Prenatal Development
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3. Trimester 1: Week 1 - 9http://www.babycenter.com/2_inside-pregnancy-weeks-1-to-9_10302602.bc
4. Trimester 1: Week 10 - 14
http://www.babycenter.com/2_inside-pregnancy-weeks-10-to-14_10308108.bc
5. Trimester 2: Week 15 - 20http://www.youtube.com/watch?v=VsjcqkOjp0U
6. Trimester 2: Week 21 - 27http://www.youtube.com/watch?v=jy091rfP0ps
7. Trimester 3: Week 28 - 37
Pregnancy MemoriesYou?Partner?Friend?Parent?
The BrainBirth 100 billion neuronsBasic architecture 1st 2 trimesters Neural tube: first 1824 daysForms the spinal cordNeural Tube DefectsEffect so severe, wont show youDefect tied to nutrition
The Course of Prenatal Development
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Neural Tube Defects
8. Neural Tube Defects http://www.youtube.com/watch?v=LUgd8Xb5W1c
The BrainNeurogenesis: 5th prenatal week:Proliferation of new immature neuronsContinues prenatal period3rd trimesterConnectivity Functioning of neurons
Fetal Learning
3rd TrimesterIncreased responsiveness:Familiar voicesDifferences in heart rate ExperimentCat in the Hat read to fetus 2xs a dayPreference for book & voice after birthAny help to development?None detected
Prenatal development3.5
Threats to prenatal development
9. Teratogens (tratogen)
Threats to prenatal developmentTeratogen Any agent that causes a birth defectSeverity & type of defect affected byDoseGenetic susceptibilityTime of exposureHazards to Prenatal Development
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All drugs (prescribed, illegal) can have effects on unborn fetusAntibiotics, analgesics, asthma medicationsX-raysPollutionLarge doses Vitamin A1961: thalidomide tragedy
Threats to prenatal development
Fetal Alcohol Syndrome
9.a. Alcohol and Fetal Alcohol Syndrome
Fetal Alcohol Syndrome
Zygote Embryonic period (wks) Fetal Period (wks)
Period of susceptibility to functional defects
Fig. 3.7 (modified)123456789163238
Teratogens and Timing of Their Effects on Prenatal DevelopmentMost serious damage from teratogens in first 28 weeks
Period of susceptibility to structural defects
Central nervous system HeartArmsEyes Legs EarsTeethPalate External genitalia
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Psychoactive DrugsPsychoactive drugs Act on nervous systemChange moodsAlter states of consciousModify perceptionsExtent of risk & harm varies
Hazards to Prenatal Development
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Look what you did to your baby
Your Doctor Wants You to Smoke 1951
Nicotine (March of Dimes longitudinal study, 2011)
Heart defects Absence or severe underdevelopment of hands, feet, radius, tibia, ulna or fibula Missing fused or extra fingers or toes Clubfoot Cleft lip or palate Eye defects Gastrointestinal defectsBaby more likely 2 or more defects
Psychoactive DrugsDangers of third-hand smoke
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Environmental HazardsFathers exposure to lead, radiationX-ray radiationPollutants & toxin wastesFertilizers & pesticidesLead-based paints PetrochemicalsWhy fathers exposure causes harm?Hazards to Prenatal Development
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Weight Gain 25 - 35 lbs. best Inadequate / excessive May affect Baby birth weightMothers healthGestational DiabetesLose weight during pregnancy?Anorexia / Bulimia
Maternal Nutrition
Maternal NutritionNutritionIncreased need for all nutrients50% increased need for:ProteinIronVitamin DCalciumPhosphorus MagnesiumWater essential Strategies for Expectant Mothers
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Maternal NutritionMaternal diet, nutrition, & weightFolic acid & ironFish: PCBs & mercury levelsMaternal ageHighest risks: adolescents, over 35 yearsDown syndromeMaternal emotional states
Hazards to Prenatal Development
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Exercise During PregnancyDecrease duration & intensity as pregnancy progressesAvoid high-risk activitiesWarm up, stretch, cool downReduce exercise significantly in last 4 weeksExercise not linked to preterm birth
Strategies for Expectant Mothers
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Parental FactorsPaternal factorsFathers diet & low vitamin CDrug use effects on spermSmoking effects of second-hand smokeFathers age at conceptionBirth defects: dwarfism, Marfans SyndromeHazards to Prenatal Development
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Prenatal tests3.6
10. Prenatal Tests
Chorionic Villus SamplingMore invasiveHigh risk pregnancy10-13 weeksEarlier than amniocentesisRemoves:Sample of chorionic villiPlacenta where attaches to uterine wall
Infertility & reproductive Choice3.7
11. How to Decide on a Fertility Treatmenthttp://www.youtube.com/watch?v=N9ReoKKtk5Q
12. Outsourcing Pregnancy
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