Tiffany

Chapter 3: The Start of Life: Genetics and Prenatal Development In this chapter we discussed how life begins. We talked about how genetics determines which traits are expressed and which are not. We also showed how a recessive trait can become dominant (see picture below). We also discussed how mutations in genes can occur and cause severe changes in cognitive and physical development, such as: Down Syndrome, Fragile X and Sickle Cell Anemia. The stages of pregnancy were also detailed in this chapter (see below) and problems that can occur while pregnant. The chapter closed with a discussion on things that can harm a baby’s development while in the womb and ways that a mother can keep her child healthy.

Transmission of Genetic information for a Recessive Trait: // Genotype //- not visible //Phenotype// - observable trait
 * Dominant/Recessive genes**—a //dominant trait// is also known as the “expressed trait”; a //recessive trait// is present in an organism, but not expressed


 * Stages of pregnancy**— //Fertilization// is when the sperm & join creating a //zygote// ; //Germinal Stage// is the 2 weeks following conception where the zygote begins to grow; //Embryonic Stage// is 2 to 8 weeks after fertilization where the //embryo// begins to develop organs & basic anatomy; //Fetal Stage// starts 8 weeks after conception and signifies the differentiation of organs and growth of the //fetus//


 * Teratogen**—a factor that produces a birth defect, this can be something like alcohol, tobacco, illegal drugs, a virus, etc; even some medications can be considered teratogens

‍Possible Questions... ‍1. If a mother and a father both carry the recessive gene for Phenylketonuria (PKU) what are the chances that their child will be affected? 2. Name and describe the four stages of pregnancy. 3. What is a teratogen? Give an example.