Objective 3 What physical traits did I inherit?

Physical Traits A. Heredity and Environment Heredity-the passing of certain inherited characteristics from one generation to the next. Chromosomes-threadlike particles in the nucleus of a cell which carry hereditary characteristics. (46 chromosomes) Genes-the parts of the chromosomes that determine all inherited characteristics.

B. Recessive and dominant genes Recessive-gene which can only determine a particular trait when paired with a similar gene. Dominant-stronger gene, predicts outcome of the trait.

C. Sex determination Male-carries x or y chromosomes in the sperm. Female-carries only x chromosomes. Boy= x + y Girl = x + x Fraternal twins-when two eggs are released at the same time and fertilized by different sperm. Identical twins-one egg is released and splits into and fertilized by one sperm.

Stages of prenatal development Objective 4.02 Stages of prenatal development

A. Terms 1. Ovum-female cell or egg is released once a month, moves through the fallopian tubes to the uterus or womb. (2-3 days) 2. Conception-egg meets with sperm and is fertilized in the fallopian tubes.

Zygote/implantation-fertilized egg travels Zygote/implantation-fertilized egg travels to the uterus and attaches itself to the thickened lining of the uterus and begins to grow. PERIOD OF THE OVUM (OVULATION, CONCEPTION, ZYGOTE-LASTS TWO WEEKS) FIRST STAGE Embryo-increasing cluster of cells- multiply. SECOND STAGE-LASTS SIX WEEKS. Major organs begin to develop. By the end of this stage the connecting tissue between the embryo and the uterus has developed into the placenta. Nourishment and oxygen from the mother's blood stream are carried from the placenta to the developing baby through the umbilical cord. Amniotic Fluid-surrounds the embryo and acts as a cushion to protect it even through minor bumps or falls of the mother.

Fetus-3RD STAGE (17TH OR 18TH WEEK OR 4-5 MONTHS), unborn baby has: 1-hair appears, 2-movement (sucking thumb, swallow, hiccup, move around) MOTHER FEELS SLIGHT FETAL MOVEMENTS. 3-Weight gain for mother 18-20 lbs.

First trimester-3 months (first three of nine months) First trimester-3 months (first three of nine months). All organs are formed and heartbeat can be heard. Second trimester-(2nd set of three months, months 4,5, & 6 of nine months) The fetus becomes more active and hair, eyelashes, and eyebrows appear. Third trimester-(last 3 months- 7,8 &9) During eighth month weight gain of fetus increases rapidly while fetal movement decreases.

Objective 4.03 Birth Defects Birth defects-abnormality that affects the structure or function of the body. Some are inherited from one or both parents. Others are caused by controllable factors in the environment.

A. Types Genetic-defective genes that match up with conception. Environmental-whether the mother's diet is nutritional, any diseases or infections that strike the mother during pregnancy, or any harmful substances such as alcohol, tobacco smoke, and drugs, exposure to outside hazards such as radiation.

Cystic Fibrosis-functional defect involving respiratory and digestive systems. Many die before adulthood. (Hereditary-Caucasian) Down's syndrome-mental retardation, delayed development, heart defects. Chromosomal error. (Extra chromosome 21) Fetal Alcohol Syndrome (FAS)-alcohol taken by mother while baby is in the womb, interferes with the tissue growth and development. The brain is most easily injured. Most all babies are mentally retarded.

Sickle-cell anemia-malformed red blood cells interfere with the supply of oxygen to all parts of the body. Symptoms include tiredness, lack of appetite, and pain. Can lead to early death. (Hereditary in African-Americans) Tay-Sachs Disease-lack of a specific chemical in the blood, resulting in the inability to metabolize fats. Leads to severe brain damage and death by age 2 or 3. (Hereditary-Jewish)

B. Prevention Genetic counseling-service combines a knowledge of heredity and birth defects with lab tests. Prenatal care- prenatal tests and care before and after baby is born.

Prenatal tests- any women 35 or older is a high-risk pregnancy Prenatal tests- any women 35 or older is a high-risk pregnancy. Prenatal tests detect birth defects. Ultrasound-uses sound waves to make a video image of the unborn child. (Low-risk to baby or mother) Amniocentesis-special needle in used to withdraw a small amount of amniotic fluid surrounding the baby. The fluid is taken to lab to inspect for defects. (risks-miscarriage) Chorionic villi sampling- (villi are fingers of tissue protruding from the chorion- the membrane encasing the fetus). Villi is used for analysis. (risks-low % of miscarrriage)