CHAPTER 2   Biological Beginnings
Mechanisms of Heredity   <ul><li>23 Chromosomes in Each Egg and Sperm </li></ul><ul><li>22 Pairs Plus Sex Chromosomes   </...
Important Terms <ul><li>Chromosomes </li></ul><ul><li>Rod-shaped portions of DNA organized into 23 pairs </li></ul><ul><li...
Behavioral Genetics <ul><li>Branch of genetics that deals with the inheritance of behavioral & psychological traits </li><...
Twin and Adopted Children Studies <ul><li>Monozygotic Twins: </li></ul><ul><li>Identical twins </li></ul><ul><li>Dizygotic...
Genetic Disorders   <ul><li>PKU   </li></ul><ul><li>Inherited disorder where an individual lacks an enzyme that converts p...
Abnormal Chromosomes   <ul><li>Abnormal Complement of 46 Chromosomes   </li></ul><ul><li>May have extra, missing, or damag...
Sickle-Cell <ul><li>A Blood Disorder that gets its name from the shape of the red blood cells that have it </li></ul><ul><...
Fragile X Syndrome <ul><li>A disorder produced by injury to a gene on the X chromosome, producing mild to moderate mental ...
Tay-Sacks Disease <ul><li>A genetic disorder that produces blindness & muscle degeneration prior to death </li></ul>
Klinefelter’s Syndrome <ul><li>A Disorder due to an extra X chromosome </li></ul><ul><li>It produces underdeveloped genita...
Genes & The Environment   <ul><li>From Genes to Behavior   </li></ul><ul><li>Genes influence Behavior Indirectly   </li></...
Genes & The Environment <ul><li>Relations Between Nature & Nurture   </li></ul><ul><li>Passive Gene-environment Relation: ...
Germinal Period (1 – 2 Weeks)   <ul><li>Fertilization </li></ul><ul><li>Begins period of Zygote   </li></ul><ul><li>Zygote...
Embryonic Period (3 – 8 Weeks) <ul><li>Embryo   </li></ul><ul><li>Once the zygote is imbedded in uterine wall it is called...
Fetal Period (9 – 38 Weeks)   <ul><li>Final & Longest Phase of Prenatal Development   </li></ul><ul><li>Ends in birth   </...
Influences on Prenatal Development   <ul><li>General Risk Factors   </li></ul><ul><li>Nutrition </li></ul><ul><li>Most wom...
Teratogens   <ul><li>Agent that causes abnormal prenatal development   </li></ul><ul><li>Drugs </li></ul><ul><li>Cigarette...
Stages of Labor   <ul><li>Stage 1 </li></ul><ul><li>May last from 12 – 14 hours for 1st birth </li></ul><ul><li>Uterus beg...
Approaches to Childbirth   <ul><li>Prepared Approaches </li></ul><ul><li>Natural Childbirth   </li></ul><ul><li>LaMaze   <...
Complications   <ul><li>Disruptions   </li></ul><ul><li>Irregular Position   </li></ul><ul><li>Breech or Shoulder-first Po...
Infant Mortality   <ul><li>Number of Infants out of 1000 births who die before their 1st birthday </li></ul><ul><li>U.S. h...
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G & D Ch. 2

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Biological Beginnings

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G & D Ch. 2

  1. 1. CHAPTER 2 Biological Beginnings
  2. 2. Mechanisms of Heredity <ul><li>23 Chromosomes in Each Egg and Sperm </li></ul><ul><li>22 Pairs Plus Sex Chromosomes </li></ul><ul><li>Polygenetic Inheritance </li></ul><ul><li>Behavioral Genetics </li></ul><ul><li>Twin and Adopted Children Studies </li></ul>
  3. 3. Important Terms <ul><li>Chromosomes </li></ul><ul><li>Rod-shaped portions of DNA organized into 23 pairs </li></ul><ul><li>Gametes </li></ul><ul><li>Sperm & ova </li></ul><ul><li>Zygote </li></ul><ul><li>Fertilized egg </li></ul><ul><li>Genotype </li></ul><ul><li>Underlying combination of genetic material in an organism </li></ul><ul><li>Phenotype </li></ul><ul><li>Observable trait </li></ul><ul><li>Polygenic Inheritance </li></ul><ul><li>A combination of genes produces a trait </li></ul><ul><li>X-Linked Genes </li></ul><ul><li>Located on the X chromosome </li></ul><ul><li>Alleles </li></ul><ul><li>Variations of genes </li></ul><ul><li>Homozygous genes </li></ul><ul><li>Alleles in a pair of chromosomes that are the same </li></ul><ul><li>Heterozygous genes </li></ul><ul><li>Alleles that are different </li></ul><ul><li>Dominant genes </li></ul><ul><li>Chemical instructions are followed </li></ul><ul><li>Recessive genes </li></ul><ul><li>Chemical instructions are ignored </li></ul><ul><li>Mutation </li></ul><ul><li>A chromosomal abnormality </li></ul>
  4. 4. Behavioral Genetics <ul><li>Branch of genetics that deals with the inheritance of behavioral & psychological traits </li></ul><ul><li>Polygenetic inheritance: </li></ul><ul><li>Phenotypes reflecting the combined activity of many separate genes </li></ul>
  5. 5. Twin and Adopted Children Studies <ul><li>Monozygotic Twins: </li></ul><ul><li>Identical twins </li></ul><ul><li>Dizygotic Twins: </li></ul><ul><li>Fraternal twins </li></ul>
  6. 6. Genetic Disorders <ul><li>PKU </li></ul><ul><li>Inherited disorder where an individual lacks an enzyme that converts phenylalanine; </li></ul><ul><li>Phenylalanine accumulates & produces toxins that harm the nervous system resulting in mental retardation </li></ul><ul><li>Huntington’s Disease </li></ul><ul><li>Inherited disorder caused by dominant gene that produces a progressive dementia; </li></ul><ul><li>On chromosome 4 </li></ul>
  7. 7. Abnormal Chromosomes <ul><li>Abnormal Complement of 46 Chromosomes </li></ul><ul><li>May have extra, missing, or damaged chromosomes </li></ul><ul><li>Down syndrome: </li></ul><ul><li>Trisomy 21 </li></ul><ul><li>For woman over 40, risk is 1 in 50 </li></ul>
  8. 8. Sickle-Cell <ul><li>A Blood Disorder that gets its name from the shape of the red blood cells that have it </li></ul><ul><li>Renders one immune to malaria but tends to die young. </li></ul>
  9. 9. Fragile X Syndrome <ul><li>A disorder produced by injury to a gene on the X chromosome, producing mild to moderate mental retardation </li></ul>
  10. 10. Tay-Sacks Disease <ul><li>A genetic disorder that produces blindness & muscle degeneration prior to death </li></ul>
  11. 11. Klinefelter’s Syndrome <ul><li>A Disorder due to an extra X chromosome </li></ul><ul><li>It produces underdeveloped genitals, extreme height, & enlarged breasts </li></ul>
  12. 12. Genes & The Environment <ul><li>From Genes to Behavior </li></ul><ul><li>Genes influence Behavior Indirectly </li></ul><ul><li>Genetic predispositions </li></ul><ul><li>Consequences of Genetic Instructions Depend on the Environment </li></ul><ul><li>Reaction Range </li></ul><ul><li>A Genotype is Manifested in Reaction to the Environment where Development Takes Place </li></ul>
  13. 13. Genes & The Environment <ul><li>Relations Between Nature & Nurture </li></ul><ul><li>Passive Gene-environment Relation: </li></ul><ul><li>Genotypes & early environment passed from parents to children </li></ul><ul><li>Evocative Gene-environment Relation: </li></ul><ul><li>Differing responses from the environment evoked by different genotypes </li></ul><ul><li>Active Gene-environment Relation: </li></ul><ul><li>Seeking environments related to genetic makeup </li></ul><ul><li>The Nature of Nurture </li></ul><ul><li>Nonshared Environmental Influences: </li></ul><ul><li>Family dynamics that make children different </li></ul>
  14. 14. Germinal Period (1 – 2 Weeks) <ul><li>Fertilization </li></ul><ul><li>Begins period of Zygote </li></ul><ul><li>Zygote is term for fertilized egg </li></ul><ul><li>Of the 200 – 500 million sperm only a few hundred will make the journey up the fallopian tubes </li></ul><ul><li>Implantation </li></ul><ul><li>When zygote burrows into uterine wall and makes connections w/blood supply </li></ul><ul><li>Germ Disc </li></ul><ul><li>Small cluster of cells near center of zygote that eventually develop into a baby </li></ul><ul><li>Placenta </li></ul><ul><li>Structure through which nutrients & wastes are exchanged between mother & baby </li></ul>
  15. 15. Embryonic Period (3 – 8 Weeks) <ul><li>Embryo </li></ul><ul><li>Once the zygote is imbedded in uterine wall it is called embryo </li></ul><ul><li>Dermal layers: </li></ul><ul><li>Ectoderm- </li></ul><ul><li>Outer layer that develops into hair, outer layer of skin & nervous system </li></ul><ul><li>Mesoderm- </li></ul><ul><li>Middle layer that develops into muscles, bones, & circulatory system </li></ul><ul><li>Endoderm- </li></ul><ul><li>Inner layer that develops into digestive system & lungs </li></ul>
  16. 16. Fetal Period (9 – 38 Weeks) <ul><li>Final & Longest Phase of Prenatal Development </li></ul><ul><li>Ends in birth </li></ul><ul><li>Baby grows & bodily systems begin working </li></ul><ul><li>Age of Viability </li></ul><ul><li>22 – 28 Weeks </li></ul><ul><li>Most systems function well enough that fetus has chance of surviving </li></ul>
  17. 17. Influences on Prenatal Development <ul><li>General Risk Factors </li></ul><ul><li>Nutrition </li></ul><ul><li>Most women need to increase calorie intake by 10% to 20% </li></ul><ul><li>Needs adequate vitamins & minerals </li></ul><ul><li>Inadequate nourishment during the last months of pregnancy can affect the nervous system & immune system of infant </li></ul><ul><li>Stress </li></ul><ul><li>Increased stress is harmful </li></ul><ul><li>Mother’s stress can reduce the flow of oxygen to the fetus which increases heart rate & activity level </li></ul><ul><li>can weaken mother’s immune system making her more susceptible to illness damaging fetal development </li></ul><ul><li>Stress can provoke smoking & drinking ending in FAS &/or premature or low-birthweight babies </li></ul><ul><li>Mother’s Age </li></ul><ul><li>Teenage motherhood </li></ul><ul><li>Incomplete education, poverty, & marital difficulties affecting child’s later development </li></ul><ul><li>Older mothers </li></ul><ul><li>Less fertility, higher chance of miscarriage & stillbirth, increased chance of Down syndrome </li></ul>
  18. 18. Teratogens <ul><li>Agent that causes abnormal prenatal development </li></ul><ul><li>Drugs </li></ul><ul><li>Cigarette Smoking constricts blood vessels reducing oxygen & nutrients to the fetus </li></ul><ul><li>Increased chance of miscarriage & low birthweight </li></ul><ul><li>Child will show signs of impaired attention, language, & cognitive skills, as well as behavioral problems </li></ul><ul><li>Diseases </li></ul><ul><li>AIDS, Genital Herpes, Rubella, Syphilis </li></ul><ul><li>Environmental Hazards </li></ul><ul><li>Lead, Mercury, PCBs, X-rays & VDTs (Latest data indicates no risk with VDTs) </li></ul><ul><li>Influence on Prenatal Development </li></ul><ul><li>Depends on the genotype of the organism </li></ul><ul><li>Impact changes over course of prenatal development </li></ul><ul><li>Each teratogen affects a specific aspect of prenatal development </li></ul><ul><li>Depends on the dosage </li></ul><ul><li>Damage is not always present at birth but can appear later </li></ul>
  19. 19. Stages of Labor <ul><li>Stage 1 </li></ul><ul><li>May last from 12 – 14 hours for 1st birth </li></ul><ul><li>Uterus begins contracting weak & irregularly </li></ul><ul><li>When stronger & more rhythmic, enlarges cervix </li></ul><ul><li>Stage 2 </li></ul><ul><li>Baby passes through cervix entering vagina </li></ul><ul><li>Mother’s pushing helps baby along </li></ul><ul><li>when top of baby’s head appears (crowning) delivery is in about 1 hour </li></ul><ul><li>Stage 3 </li></ul><ul><li>Lasts only a few minutes </li></ul><ul><li>Mother’s pushing expels the placenta </li></ul>
  20. 20. Approaches to Childbirth <ul><li>Prepared Approaches </li></ul><ul><li>Natural Childbirth </li></ul><ul><li>LaMaze </li></ul><ul><li>LeBoyer </li></ul><ul><li>Cesarian </li></ul>
  21. 21. Complications <ul><li>Disruptions </li></ul><ul><li>Irregular Position </li></ul><ul><li>Breech or Shoulder-first Position </li></ul><ul><li>Enlarged Head </li></ul><ul><li>Anoxia: Umbilical cord shuts off oxygen </li></ul><ul><li>Preterm </li></ul><ul><li>Low Birthweight </li></ul>
  22. 22. Infant Mortality <ul><li>Number of Infants out of 1000 births who die before their 1st birthday </li></ul><ul><li>U.S. has very HIGH infant mortality </li></ul><ul><li>Most other countries provide extensive care for little or no cost </li></ul>

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