A Closer Look at Conception

Introduction: The Genetic PackageEach of us inherits 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. EX: asthma, diabetes, some cancers, cystic fibrosis

Making A Unique Person

Each sperm & egg cell contains a different combination of genes. Sperm: MaleEgg: Female

These cells combine during the fertilization process and produce a unique individual.

ChromosomesTiny threadlike particles located in the nucleus of every cell.

Chromosomes are what make up our genetic package46 chromosomes = 23 pairs

GenesEach 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.

GenesIf both inherited genes are the same- then the child will have that characteristic.

If they are different- the dominant gene will be expressed in the child.

Dominant: STRONGER geneRecessive: WEAKER gene

Let’s Understand Genes (eye color)

B= Brown Dominant b= Blue recessive

Dad (Bb)Mom (Bb)

Child 1 Child 2 Child 3 Child 4

(BB) (Bb) (Bb) (bb)

Determining SexThe 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 girlXY= baby boy

Multiple Births

Identical Twins: 1 egg divides in half soon after fertilization. Each half grows and divides. 1 Zygote (the egg and sperm combined) becomes 2.

Fraternal Twins: 2 eggs are released and both become fertilized

Identical Fraternal

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

More 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.

Videos about Infertility In Vitro Fertilization:

http://video.nationalgeographic.com/video/ivf-sci Ovum Transfer:

https://www.youtube.com/watch?v=pGeIYV1HoP4 Artificial Insemination:

https://www.youtube.com/watch?v=S6FmkzOf9ao

Let’s Review

1. List 3 traits that are inherited.

2. Explain how dominant and recessive genes work.

3. How is the sex of a baby determined?

4. What is the difference between identical twins and fraternal twins?

5. What are some disadvantages of fertility drugs?