Chapter 3 Forming a New Life PDF

Forming a New Life Chapter 3 Genetic Testing and Engineering Genomics—the study of functions and interactions of various genes Genetic testing: Should children be tested? Would you want to know if you were predisposed for a particular disease? Are there potential...

Forming a New Life Chapter 3 Genetic Testing and Engineering Genomics—the study of functions and interactions of various genes Genetic testing: Should children be tested? Would you want to know if you were predisposed for a particular disease? Are there potential ethical and moral issues with genetic testing? Guideposts for Study § How does conception normally occur, and what causes multiple births? § How does heredity operate in determining sex and transmitting normal and abnormal traits? § How do scientists study the relative influences of heredity and environment, and how do heredity and environment work together? § What roles do heredity and environment play in physical health, intelligence, and personality? Guideposts for Study § What are the three stages of prenatal development, and what happens during each stage? § What environmental influences can affect prenatal development? § What techniques can assess a fetus’s health, and why is prenatal care important? Conceiving New Life § Fertilization ú Union of sperm and ovum to produce a single-celled zygote ú Also called conception Two Types of Multiple Births § Monozygotic (MZ) ú One egg – One sperm ú Identical twins ú Share 100% of genes § Dizygotic (DZ) ú Two eggs – Two sperm ú More common ú Fraternal twins ú Share 50% of genes – just like non-twin siblings  Rise in Multiple Birth Rate § Factors ú Rising trend toward delaying childbirth ú Increasing use of fertility drugs § Related Risks ú Pregnancy complications ú Premature delivery and lower birth weight ú Infant disability or death Fetal Development 9 months in the womb lhttps://www.youtube.com/watch?v=WH9ZJu4wRUE Mechanisms of Heredity: DNA Determination of Sex  Sex Determination § Chromosomes: Coils of DNA carrying genes ú Autosomes: ú 22 pairs not related to sexual expression ú Sex chromosomes: ú 1 pair determining sex ú XX = female ú XY = male  Dominant and Recessive Inheritance § Dominant ú Heterozygosity, with a dominant allele § Recessive ú Homozygosity, with no dominant allele  Trait Inheritance § Alleles ú Homozygous: Identical copies of gene ú Heterozygous: Different copies of gene § Polygenic inheritance ú Interaction of several genes for a trait ú Most traits Dominant-Recessive Inheritance: Tongue Curling Example I  Gene Expression § Genotype § Actual genetic makeup or allele combinations § Tongue curling ability: DD or Dd § Phenotype § Observable expression of genetic makeup § Product of the genotype § Multifactorial transmission § Experience modifies the expression of a genotype  Epigenesis § Epigenetic framework or chemical molecules that alter the way a cell “reads” the gene’s DNA § Epigenetic markers may contribute to cancer, diabetes or heart disease § Epigenetic markers may change due to environment factors § Imprinting  Inherited Defects § Dominant abnormal gene § Recessive abnormal gene § Incomplete: Partial dominance § Trait is not fully expressed § Sickle-cell anemia: Only some parts of the disease are expressed Sex-Linked Inheritance Sex-Linked Defects § Disorders linked to genes on sex chromosomes § Red/green color blindness, hemophilia § Affects males and females differently § Carrier § Individual unaffected by disorder but passes on gene to offspring  Chromosomal Abnormalities § Errors in cell division § Result in missing or extra chromosomes § Can occur in sex chromosomes or autosomes  Down Syndrome § Trisomy 21 – an extra 21st chromosome § Most common autosomal disorder § Responsible for 40% of moderate to severe mental retardation Genetic Counseling § Helps prospective parents assess risk of bearing a child with a genetic defect § Karyotype chart shows chromosomal abnormalities § Especially helpful when: ú Already have biological children with defect ú Family history ú Ethnicity Behavioral Genetics § How does heredity and environment influence traits? § Heritability: § Statistical estimate of heritable influence on trait variance in a population § Nature vs nurture: § https://www.youtube.com/watch?v=tbSgU41FIac  Measuring Heritability § Family Studies § The degree to which bio-relatives share traits § Adoption Studies § The degree to which adopted children resemble biological relatives or adopted family members § Twin Studies § Concordance: The degree to which MZ and DZ twins resemble each other for a trait  Heredity & Environment: Working Together § Reaction Range: Potential variation in a trait § Canalization: Heritable restrictions on the range of trait development Intelligence and Reaction Range  Genotype-Environment (G x E) Correlations § Environment reflects or reinforces genetic differences ú Passive: Parents provide environment that fosters trait ú Reactive or evocative: Based on their traits, children evoke different responses from others ú Active or niche picking: choosing an environment that suits your traits Nonshared Environment § Development reflects unique environment in which each child grows up ú Accidents ú Illnesses ú Unique interactions with friends or peers  Traits Influenced by Heredity & Environment § Obesity § Intelligence, school achievement § Personality § Schizophrenia Stages of Prenatal Development Stage Duration Germinal Conception to 2 weeks Embryonic 2 to 8 weeks Fetal 8 weeks to birth Germinal Stage Development Embryonic Stage Characteristics § Organs and major body systems develop rapidly ú Respiratory ú Digestive ú Nervous § Risk of spontaneous abortion, or miscarriage Development During Fetal Stage § Organs and body become more complex § “Finishing Touches” – toenails, eyelids § Appearance of bone Maternal Factors § Teratogenic: birth defect producing § Nutrition and maternal weight § Drug and alcohol intake § Nicotine § Caffeine § Maternal illnesses § Sexually transmitted diseases (HIV/AIDS) § Maternal age and stress § Outside environmental hazards Paternal Factors § May affect quality of sperm: ú Exposure to lead ú Marijuana or tobacco smoke ú Alcohol or radiation ú Pesticides ú Paternal age Monitoring Prenatal Development § Ultrasound and amniocentesis § Chorionic villus sampling CVS) § Embryoscopy § Maternal blood test Prenatal Care § Includes: ú Education ú Social services ú Nutritional services < Helps protect the life and health of the infant and mother § Not evenly distributed among SES, ethnic groups Preconception care § CDC recommendations include: § Physical examinations § Vaccinations § Risk screening § Counseling