Download A Closer Look at Conception

 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.
 Tiny
threadlike particles located in
the nucleus of every cell.
 46 chromosomes = 23 pairs
 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.
 If
both inherited genes are the samethen the child will have that
characteristic.
 If they are different- the dominant
gene will be expressed.
 Dominant- stronger gene.
 Recessive- weaker gene.
 Ex:
B= Brown Dominant, b= Blue
recessive.
Dad (Bb)
Mom (Bb)
Child 1
(BB)
Child 2 Child 3
(Bb)
(Bb)
Child 4
(bb)
 Each
sperm & egg cell contains a
different combination of genes.
 These cells combine during the
fertilization process and produce a
unique individual.
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

 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
 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.
 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.
1.
2.
3.
4.
5.
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?
 Heredity
in the Works Worksheet