Learning Objectives Unit Two Chapter Three 1 Define genotype and phenotype and describe the differences between them What are genes and how are they transmitted between generations through mitosis and meiosis Genotype the complex blend of genetic information that determines our species and influences all our unique characteristics Phenotype directly observable characteristics Gene a segment of DNA along the length of chromosome Mitosis the process by which a DNA can duplicate itself chromosomes copy themselves As a result each new body cell contains the same number of chromosomes and the identical genetic information Meiosis a cell division process that forms gametes by halving the number of chromosomes normally present in body cells When sperm and ovum unite at fertilization the resulting cell called a zygote will again have 46 chromosomes They do this by crossing over when chromosomes next to each other break at one or more points along their length and exchange segments so that genes from one are replaced by genes from another 2 What determines the sex of a child What are gametes and zygotes The 23rd pair of chromosomes are the sex chromosomes which determine the sex of the child IN females this pair is XX in males it is XY The sex of the new organism is determined by whether an X bearing or a Y bearing sperm fertilized Gametes sex cells the sperm and ovum Zygotes new fertilized cell formed by the union of sperm and ovum at the ovum conception 3 What are the two types of twins and how are they created Monozygotic identical twins zygote that has started to duplicate separates into two clusters of cells that develop into 2 individuals Fraternal dizygotic twins most common type of multiple birth result from the release and fertilization of 2 ova 4 Describe basic patterns of genetic inheritance including examples of each type and implications of inheritance e g homozygous dominant heterozygous dominant homozygous recessive Each form of a gene is called an allele one from father and one from mother If the alleles from both parents are alike the child is homozygous and will display the inherited trait If the alleles differ than the child is heterozygous and relationships between the alleles determine the phenotype Homozygous dominant DD dark hair Heterozygous dominant Db dark hair Homozygous recessive bb blond hair Still heterozygous individuals with just one recessive allele Db can pass that trait to their children and are called carriers of the trait Incomplete dominance a pattern of inheritance in which both alleles are expressed in the phenotype resulting in a combined trait or one that is intermediate between the two sickle cell anemia 5 Describe conception and the three periods of prenatal development What are the milestones of each period Conception ovum bursts from one of a woman s ovaries and is drawn into one of the two fallopian tubes that lead to the uterus While the ovum is traveling the spot on the ovary from which it was released the corpus luteum secretes hormones that prepare lining of the uterus to receive a fertilized ovum The sperm travel upstream in the female reproductive tract through the cervix the opening of the uterus and into the fallopian tube where fertilization takes place The sperm that survive penetrate the surface of the ovum When one sperm succeeds in fertilizing the ovum the resulting zygote begins to duplicate 6 What are teratogens What factors affect how teratogens impact prenatal development Give examples of known teratogens and describe how it is difficult to determine how environmental agents impact prenatal development period effects Teratogen any environmental agent that causes damage during the prenatal Depends on the following factors 1 Dose larger doses over longer time periods usually have more negative 2 Heredity genetic makeup of mother and developing organism some individuals are better able than others to withstand harmful environments 3 Other negative influences presence of several negative factors at once such as additional teratogens poor nutrition and lack of medical care can worsen the impact of a single harmful agent 4 Age effects of teratogens vary with age of the organism at time of exposure Embryonic period is the time when serious defects are most likely to occur because the foundations for all body parts are being laid down During the fetal period teratogenic damage is usually minor Effects may not show up for decades Teratogens thalidomide diethylstilbestrol DES Acutane Isotretinoin aspirin caffeine anti depressants radiation environmental pollution maternal disease 7 Name and describe how other maternal factors impact development What are the complications of maternal obesity Maternal exercise nutrition and emotional well being affect the embryo and fetus Regular Exercise increased birth weight and reduction in risk for complication such as maternal diabetes and high blood pressure Vigorous exercise lower birth weight Nutrition healthy diet results in maternal weight gain of 25 to 30 pounds Malnutrition more miscarriages give birth to babies with physical defects underweight and had small heads loss of brain weight baby s have poor immune systems distort structures of organs irritable irresponsive to stimulation high pitched cry NEED FOLIC ACID Emotional well being intense anxiety associated with higher rates of miscarriage prematurity low birth weight infant respiratory and digestive illnesses colic sleep disturbances and irratibilty Maternal age complications increase after thirties and spike with women 50 55 Maternal obesity can lead to gestational diabetes and the risk for the fetus is still birth After birth the child and mother are at risk for heart disease hypertension and future obesity 8 What are the three stages of childbirth 9 What are the purposes and features of the Apgar scale What does the scale imply The Apgar Scale assess the baby s physical condition Rating of 0 1 or 2 on each 5 characteristics is made at 1 minute and 5 minutes after birth A combined score of 7 or better indicates that the infant is in good physical condition 10 What are the risks associated with preterm and low birth weight infants Brain abnormalities frequent illness inattention overactivity sensory impairments poor motor coordination language delays low intelligence test scores deficits in school learning and emotional and behavior problems Small for date infants usually have more serious problems During first year they are more
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