1. A Closer Look at Conception Chapter 3 Section 2

2. The Genetic Package • Nature– Genetics/ Heredity • Physical build • Skin color • Hair texture/color • Color/shape of eyes • Shape/size of ears, hands, and feet • Blood type

3. Moment of Conception • _____ chromosomes • 23 from ______ (father) • 23 from mother (_____) • Each contains genes • Determine characteristics • ____ genes for each characteristic • One from mom, one from dad

4. Dominant Vs. Recessive • When both genes ________, the child will receive that trait • Ex: both parents pass the blue-eyed trait, child will have blue eyes • When different, the _________ trait will win • Ex: brown-eyed trait (D) vs blue-eyed trait (R): the child will have _______ eyes

5. Gene Pool • How are the genes picked? • Matter of _________ • Create an _________ individual • Siblings will look similar but ________________ __________________

6. How Does it Work??? • What does this mean? • BB: 2 dominant= brown • Bb: brown • bb: Blue eye • 1 in 4 chance of blue eyes

7. Sex Determination • Gender is determined by 2 chromosomes • ____________ • The _____ contains ___ • Sperm – __________ • During fertilization • XX= ______________ • XY= ______________

8. Multiple Births • Beginning of _____________the cell divides into 2 • Continue until they divide into millions • Sometimes the growing mass divides into 2 • Grow into separate ______________ • Produces _____________ twins

9. Identical Twins • Dividing mass of cells • Form 2 embryos • Same ______ • Very similar characteristics • Due to the same _______ and same _________ • If the split is not complete- ___________ twins occurs

10. Fraternal Twins • Results when 2 eggs are released at the _________________ • Each fertilized by different _________ • Not always the same sex • No more alike than ordinary ___________

11. Multiple Births • In more than 2 births: • Can be identical, fraternal, or both • Example: triplets • One ovum could divide into 3 parts (_________) • 2 eggs are fertilized and one splits (2 identical & one fraternal) • ______ eggs released at once (_____________)

12. Genetic Worksheet