Prenatal development
Identify the role of genes and chromosomes in the development of the fetus.
* The human zygote is the cell that is formed by the union of the sperm and ovum. contains one set of 23 chromosomes from the mom nd another set from the dad. 46 chromosomes arranged in 23 pairs. Chromosomes are composed of long, threadlike molecules of DNA which twist around to form a spiral staircase or a double.
1. Human development begins one cell zygote (zygote). * DNA contains app 20k-25k genes, the basic unit of heredity. Some traits such as Huntington disease, are cause by single gene. Most human traits result combined effect diff genes.
2. The zygote contains 23 chromosomes from each parent, arranged in pairs, for a total of 46_.
3. What are monozygotic twins? Dizygotic twins? *MONOZYGOTIC TWINS- identical twins, come from the same fertilized egg and contain the same genetic instruction. Happens during early age at cell division, fertilized egg can divide 2 cluster that develop 2 diff fetuses. DIZYGOTIC TWINS- or fraternal, develop from 2 diff eggs. are most common. similar as biological siblings. share similar prenatal and postnatal environment. the factors linked to fraternal twin are maternal age, ethnicity, nutrition, # of births, and exposures to fertile drugs.
4. What is fragile x-syndrome? * one of the leading causes of mental retardation and developmental disabilities. Caused by single gene is more common is man not woman. Associated with cleft palate, abnormal EEG's, disorder in eyes and characteristic facial appearance. May display unusual interaction w other people. Can be detected through genetic screening and DNA analysis.
Outline what occurs during the 3 stages of prenatal development.
1. Germinal, embryonic, fetal. * GERMINAL(0-4days)- fertilization, cell division, Zygote travels down fallopian tube to uterus. Implantation begins. Implantation finish. EMBRYONIC(weeks)- Placenta behind to form. Heart begins to beat, eyes, blood vessels, and nervous system begins to develop. Arms and legs begins to forms, gonads begin to form. Develop of major organ completed, pregnancy detected by physical exam. FETAL(8-12weeks)- appearance of genital, arms and leg moving, circulation system function. Response stimulation. Skin and hair develop, skeleton hardens. heart beat is heard vigorous movement. gain weight. eyes open. respiratory system matures (can be out). Gain layer of fat under skin. Survive outside womb. Birth(38)
Identify environmental factors that may negatively affect prenatal development.
1. Teratogens, disease, etc. Describe the outcomes. * TERATON- any environmental substance or disease that cause abnormal development of the fetus is called teraton. certain disease such as rubella, mumps, chicken pox, malaria, can affect developing fetus. The frequent use of alcohol during pregnancy is one of the leading cause of mental retardation. rubella mumps etc, affect the development of the fetus. A fetus is most vulnerable to environment influences during sensitive period when the body part and major organ are developing. woman who took drug between 38 to 46 days after conception, gave birth to babies with deformed arms, 46 to 48 days, babies were born with deformed legs. Other teratogens have a threshold effect; 1 or more aspirin during pregnancy may harm the fetus. but frequent use may lower babes birth weight, increase fetal and death.
2. What is the leading cause of infant mortality? low birth. a short gestation period
Identify the role of experience in brain development. * Early experiences are crucial in stimulating the development and pruning of the neural synapses. * contingent nurturing is most important for early brain stimulation * neuroscientist are on the verge of significant new discoveries about early brain development with recent technological advances.
1. What is the sensitive period? What is plasticity? * Permanent deficits are likely if vital experience do not occur