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Slide 1: “This multimedia product and its contents are protected under copyright law. The following are prohibited by law: • any public performance or display, including transmission of any image over a network; • preparation of any derivative work, including the extraction, in whole or part, pf any images; • any rental, lease, or lending of the program.” “Copyright © Allyn & Bacon 2007”
Slide 2: Conception and Genetics • The Process of Conception – Ovum – Sperm • The Journey of Sperm toward Ovum • Chromosomes – – – – 23 pairs DNA Genes X and Y chromosomes Gametes (Ovum & Sperm) – Meiosis – Only 23 chromosomes “Copyright © Allyn & Bacon
Slide 3: Figure 2.1 “Copyright © Allyn & Bacon
Slide 4: Conception and Genetics • Homozygous pair – When the two sets of instruction are the same at any given locus • Heterozygous pair – When the two sets of instruction are different at any given locus “Copyright © Allyn & Bacon
Slide 5: Conception and Genetics • – Polygenic Inheritance Many genes blend together to increase the genetic outcomes seen in the phenotype • – Multifactorial Patterns Expression of traits that are influenced by both genes and environment • – Genomic Imprinting Some genes are biochemically marked at the time ova and sperm develop • – Mitochondrial Inheritance Genes passed only from mother to child “Copyright © Allyn & Bacon
Slide 6: Conception and Genetics • Genotype – the genetic blueprint • Phenotype – observable characteristics • Dominant-recessive pattern – Dominant genes always express their characteristics – Recessive genes come in pairs to express their characteristics “Copyright © Allyn & Bacon
Slide 7: Figure 2.2 “Copyright © Allyn & Bacon
Slide 8: Figure 2.3 “Copyright © Allyn & Bacon
Slide 9: Conception and Genetics • Twins – Identical – Fraternal • Twins in genetic research “Copyright © Allyn & Bacon
Slide 10: Development from Conception to Birth 3 Stages of Prenatal Development – The Germinal Stage – the zygote • From conception to implantation – Lasts from 10 days to 2 weeks • Blastocyst divides into 2 sections – Section that will become the baby – Specialization of cells needed to support development – » Placenta » Umbilical cord » Yolk sac » Amnion “Copyright © Allyn & Bacon
Slide 11: Figure 2. 4 “Copyright © Allyn & Bacon
Slide 12: Development from Conception to Birth 3 Stages of Prenatal Development – The Embryonic Stage • • • • Forms the foundations of all body organs Neural tube develops All major organs and systems begin to develop By week 7, the Y chromosome directs the development of the penis with the help of testosterone “Copyright © Allyn & Bacon
Slide 13: Development from Conception to Birth 3 Stages of Prenatal Development – The Fetal Stage • Growth from 1/4th ounce and 1 inch to 7 ½ pounds and 20 inches in length • • • • • Refinement of all organ systems Surfactant Vernix Age of viability - week 24 Engagement “Copyright © Allyn & Bacon
Slide 14: The Fetal Stage Continued • Nervous System – Neural tube develops at week 4 – Glial Cells • Provides the glue that holds the nervous system together • Helps remove debris after neuronal death • Segregates neurons from each other “Copyright © Allyn & Bacon
Slide 15: Figure 2.5 “Copyright © Allyn & Bacon
Slide 16: The Fetal Stage Continued • Nervous System – Neurons • Dendrites – Major receptors of nerve impulses • Axons – Primary transmitting apparatus • Synapses – Fluid-filled gap between neurons – allow neurotransmitters to pass between neurons – Most neurons are born between 10 and 18 weeks “Copyright © Allyn & Bacon
Slide 17: Figure 2.6 “Copyright © Allyn & Bacon
Slide 18: Sex Differences in Prenatal Development • Between week 4 and 10, males begin to secrete testosterone from primitive testes • Necessary to develop male genitalia • Lack of testosterone will “demasculinize” the male embryo • Too much testosterone will defeminize the female embryo • Prenatal hormones may influence sex differences in: – – – – Brain development Hormones in adolescence Levels of physical aggression Relative dominance of right and left hemispheres “Copyright © Allyn & Bacon
Slide 19: Sex Differences in Prenatal Development • Girls – Slightly faster skeletal development • Boys – Slightly heavier and longer at birth – More vulnerable to prenatal problems – More likely to be aborted spontaneously – Have more birth injuries and birth defects – X-related problems may be a factor – Slightly more active before birth “Copyright © Allyn & Bacon
Slide 20: Prenatal Behavior • Fetuses respond to sound with body movements as early as 25 weeks • Can distinguish between familiar and novel stimuli by 32 weeks • Learning may begin prenatally – “The Cat in the Hat” experiment • Music played prenatally may lead to advanced motor and cognitive skills at six months “Copyright © Allyn & Bacon
Slide 21: Questions to Ponder? • How would you deal with a risk of passing on a severe genetic illness to any child that you and your partner might have? • If you are having a baby, would you add music and reading to your child prenatally to your pregnancy routine? Why or why not? “Copyright © Allyn & Bacon
Slide 22: Problems in Prenatal Development Genetic Disorders • Autosomal Disorders – Caused by recessive genes • Phenylketonuria (PKU) • Sickle-cell disease • Tay-Sachs disease – Caused by dominant genes • • • • Huntington’s disease Schizophrenia Migraine headaches Extra fingers “Copyright © Allyn & Bacon
Slide 23: Problems in Prenatal Development Genetic Disorders • Sex-linked Disorders – Red-green colorblindness – Hemophilia – Fragile-X syndrome – Caused by recessive gene on X chromosome – Boys suffer more often than girls “Copyright © Allyn & Bacon
Slide 24: Figure 2.7 – Sex Linked Transmission of a Recessive Disease “Copyright © Allyn & Bacon
Slide 25: Problems in Prenatal Development Chromosomal Errors • Trisomies – Trisomy 21 – Down Syndrome • Mental retardation • Distinctive facial features • Physical abnormalities – Maternal age is a major factor “Copyright © Allyn & Bacon
Slide 26: Problems in Prenatal Development Chromosomal Errors • Sex Chromosome Anomalies – XXY – Klinefelter’s syndrome – XO – Turner’s syndrome – XXX – girls with an extra X – XYY – boys with an extra Y “Copyright © Allyn & Bacon
Slide 27: Problems in Prenatal Development Teratogens: Maternal Diseases • Rubella – Vaccinations should be given to all children • HIV • Other sexually transmitted diseases – Syphilis – Genital herpes – Gonorrhea – Cytomegalovirus “Copyright © Allyn & Bacon
Slide 28: Figure 2.8 “Copyright © Allyn & Bacon
Slide 29: Problems in Prenatal Development Other Maternal Influences • Chronic Illnesses – Heart disease, diabetes, lupus, hormone imbalances can all lead to developmental delays • Fetal-maternal medicine helps to manage the effects of long-term illnesses “Copyright © Allyn & Bacon
Slide 30: Problems in Prenatal Development Environmental Hazards • Limiting exposure to mercury • Avoiding possible harmful chemicals – – – – – Lead Arsenic Anesthetic gasses Solvents Parasite-bearing substances “Copyright © Allyn & Bacon
Slide 31: Problems in Prenatal Development Teratogens: – Substances that cause damage to an embryo – Each organ system is most vulnerable to harm when its development is most rapid (Figure 2.8) – The first 8 weeks are the most dangerous “Copyright © Allyn & Bacon
Slide 32: Problems in Prenatal Development Teratogens: Drugs • Smoking • Drinking – Fetal Alcohol Syndrome • Cocaine • Marijuana and Heroin “Copyright © Allyn & Bacon
Slide 33: Problems in Prenatal Development Other Teratogens and Maternal Factors • Vitamin A – large doses may cause malformations of head, face, heart • Aspirin • Lead – may lead to lower IQ – 3–6% infants and young children have high levels of lead – Most are black or Hispanic children in inner cities “Copyright © Allyn & Bacon
Slide 34: Problems in Prenatal Development Other Maternal Influences • Diet – Both general adequacy and the presence of certain key nutrients are essential in a pregnant woman’s diet • Subnutrition – a diet that is barely adequate and lacking in some essential nutrients • Folic acid deficiencies – risk in neural tube defects – Malnutrition (Especially before 3 months prenatally) • Low birth weight • Brain stunting • Fetal death – A woman’s caloric needs go up 10-20% during pregnancy “Copyright © Allyn & Bacon
Slide 35: Problems in Prenatal Development Other Maternal Influences • Age – First pregnancies occurring later – 25.1 years – Women over 35 have higher risks for pregnancy complications – Teenage mothers • May suffer from poverty and poor prenatal care • Children may exhibit learning and behavior problems in school • Both preterm and low birth weight babies were twice as common in preteen mothers “Copyright © Allyn & Bacon
Slide 36: Problems in Prenatal Development Maternal Emotions • Stress – Can change hormone levels • Stressful life events, emotional distress, and physical stress are linked to slight increases in problem pregnancies • Severely distressed mothers produce infants who grow slowly • Social support and counseling may help “Copyright © Allyn & Bacon
Slide 37: Problems in Prenatal Development • Poverty – Low birth weight or stillborn babies are more common in poor mothers – More likely to have earlier pregnancies – Good prenatal care may help overcome difficulties “Copyright © Allyn & Bacon
Slide 38: 2 End Show “This multimedia product and its contents are protected under copyright law. The following are prohibited by law: • any public performance or display, including transmission of any image over a network; • preparation of any derivative work, including the extraction, in whole or part, pf any images; • any rental, lease, or lending of the program.” “Copyright © Allyn & Bacon 2007”