A Closer Look at Conception The Developing Child Chapter 5 Section 2

Introduction: The Genetic Package Each of us inherit many personal characteristics from our parents. EX: physical build, skin color, hair color & texture, eye color & shape. Just as personal traits can be passed on, so can medical conditions.

Chromosomes Tiny threadlike particles located in the nucleus of every cell. 46 chromosomes = 23 pairs

Genes Each chromosome contains several genes. Genes- the unit that determine the child's inherited characteristics. Genes makeup chromosomes as beads make up a necklace. For every inherited characteristic, a person receives 2 copies- 1 from mom and 1 from dad.

Genes If both inherited genes are the same- then the child will have that characteristic. If they are different- the dominant gene will be expressed. Dominant- stronger gene. Recessive- weaker gene.

Genes Ex: B= Brown Dominant, b= Blue recessive. Dad (Bb) Mom (Bb) Child 1 Child 2 Child 3 Child 4 (BB) (Bb) (Bb) (bb)

Making A Unique Person Each sperm & egg cell contains a different combination of genes. These cells combine during the fertilization process and produce a unique individual.

Determining Sex The sex of a child is determined at conception. Every egg cell contains an X chromosome. Each sperm cell will contain either an X or a Y chromosome. The sex of the child is determined by the chromosome carried by the sperm that fertilizes the egg. XX= baby girl XY= baby boy

Multiple Births Identical Twins= 1 egg divides in half soon after fertilization. Each half grows and divides. 1 Zygote becomes 2. Fraternal Twins= 2 eggs are released and both becomes fertilized

Infertility Infertile- inability to conceive a child. There are many causes of infertility in both men and women. Options for Infertile Couples: Adoption- a couple legally takes on all responsibilities and rights for raising, loving, and caring for a child in need of a permanent home. Artificial Insemination- doctor injects sperm into the uterus. Sperm may be the husband’s or from a donor.

Infertility Options for Infertile Couples: In Vitro Fertilization- Doctor combines a mature ovum from the woman with sperm from her husband. If the ovum becomes fertilized then the doctor places it in the uterus. Ovum Transfer- Similar to In Vitro, except that the ovum is donated by another woman. It is fertilized in the laboratory and placed in the uterus. Surrogate Mother- A surrogate mother is a substitute woman who becomes pregnant to have a baby for another woman.

Let’s Review List 3 traits that are inherited. Explain how dominant and recessive genes work. How is the sex of a baby determined? What is the difference between identical twins and fraternal twins? What are some disadvantages of fertility drugs?

Assignment Heredity in the Works Worksheet