2. 4
Pregnancy 2

3. Conception
Cell is the smallest unit of life that is able to reproduce itself
Sperm is the male germ cell
Ovum is the female germ cell
Conception occurs when ovum and sperm combine
Zygote is a single cell formed at conception
also called a fertilized egg
continued

4. Conception Fallopian tubes extend from the sides of the uterus
where the ovum is fertilized
Uterus is the organ in which the baby develops

5. Genetic Factors and the Unborn Baby
Genetic factors are traits passed through the genes
affect all stages of growth and development
Genome is a genetic blueprint that guides growth and development during pregnancy
gives cells instructions for family-like traits that will unfold throughout life
continued

6. Genetic Factors and the Unborn Baby
Nucleus is the center of the cell
Genetic code is a set of instructions for development
DNA store the genetic code
Chromosomes carry the DNA

7. Objective
Describe how a person inherits traits through genes.

8. Chromosomes and Genes Chromosomes Genes
each person has 46, pairs of 23
half from sperm, half from egg
contains 20,000 genes
Genes
each human cell contains about 1 million genes
a gene, or group of genes, decides a trait

9. Dominant and Recessive Traits
Dominant traits always show in a person even if only one gene of the pair is inherited for that trait
Recessive traits typically do not show in a person unless both genes for the trait are inherited
one from each parent
person who inherits only one recessive gene for a trait becomes a carrier of that trait

10. Sex Chromosomes Sex chromosomes determine genetic sex of baby
XX female
ovum always carries only X chromosomes
XY male
sperm can carry either X or Y chromosome
boys’ sex-linked traits are determined only by their mothers

11. Multiple Pregnancy
Multiple pregnancy occurs when two or more babies develop in the same pregnancy
continued

12. Multiple Pregnancy Fraternal children develop from two or more ova
most common
each baby has own chorion
Identical children develop from same ova and sperm
Mixed types of pregnancy must include fraternal and identical babies

13. What Do You Think?
How can parents help identical twins maintain separate identities while still nurturing a close sibling relationship?

14. Stages in Prenatal Development
Prenatal development takes place between conception and birth
germinal stage
embryonic stage
fetal stage

15. Germinal Stage Germinal stage is the first stage of development
continued

16. Germinal Stage
Amnion is a fluid-filled sac that surrounds the baby in the uterus
Placenta is an organ filled with blood vessels that nourish the baby in the uterus
Umbilical cord is a cord that connects the baby to the placenta

17. Embryonic Stage
Embryonic stage is the second stage of development, lasts about six weeks
most crucial to development
baby is called an embryo
development of most body systems
heart begins to beat
cartilage is present before bones form
substances pass from mother’s placenta through the umbilical cord

18. Fetal Stage
Fetal stage is the third stage of pregnancy, lasts from about nine weeks after conception until birth
bone starts to replace cartilage
baby is known as a fetus
continued

19. Fetal Stage During the fetal stage, all parts of the body mature
overall size increases quickly
hear heartbeat in the third month
quickening begins between the fourth and fifth months
continued

20. Fetal Stage
Age of viability is the age at which a baby could survive if born, 28 weeks
still need extensive medical care
better chance of survival each week the baby is not born
During last two months of pregnancy,
inner layer of lungs produces substance that allows for breathing air
receives immunities from mother in the ninth month

21. What Do You Think?
Pregnancies that end before 20 weeks are considered a miscarriage, resulting in no record of the life, such as a birth or death certificate.
How do you think this impacts a parent after the loss of a wanted pregnancy?

22. Glossary of Key Terms
age of viability. Age at which most babies could survive if they were born (28th week of pregnancy).
amnion. Fluid-filled sac that surrounds the baby in the uterus.
cartilage. Soft, elastic, flexible tissue that provides structure for the body.

23. Glossary of Key Terms
cell. Smallest unit of life that is able to reproduce itself.
chorion. Membrane that surrounds the baby in the uterus.
chromosomes. Threadlike structures that carry genes in living cells.
conception. Union of the ovum and sperm cells.

24. Glossary of Key Terms
dominant traits. Traits that always show in a person even if only one gene of the pair is inherited for that trait.
embryo. Medical term used to describe the unborn baby in the embryonic stage of development (week 3 through 8 of pregnancy).

25. Glossary of Key Terms
embryonic stage. Second stage of prenatal development, lasting about six weeks.
fallopian tubes. Two hollow tubes that connect to the uterus and have fingerlike projections that reach toward each ovary.
fetal stage. Third stage of pregnancy, lasting from about nine weeks after conception until birth.

26. Glossary of Key Terms
fetus. Medical term used to describe the unborn baby in the fetal stage of development (week 9 until the end of pregnancy).
fraternal. Term used to describe children from multiple pregnancies who develop from two or more fertilized ova and differ in genetic makeup.

27. Glossary of Key Terms
genetic factors. Traits that are passed through the genes.
germinal stage. First stage of prenatal development, lasting about two weeks after conception.
identical. Term used to describe children from multiple pregnancies who develop from one fertilized ovum and have the same genetic makeup.

28. Glossary of Key Terms
multiple pregnancy. Pregnancy in which two or more babies develop.
ovum. Female sex cell; also called egg.
placenta. Organ filled with blood vessels that nourish baby in the uterus.
prenatal development. Development that takes place between conception and birth.

29. Glossary of Key Terms
quickening. Movements of the fetus that can be felt by the mother.
recessive traits. Traits that typically do not show in a person unless both genes for the trait are inherited.
sperm. Male sex cell.
umbilical cord. Cord that connects the baby to the placenta.

30. Glossary of Key Terms
uterus. Organ in which the baby develops and is protected until birth.
zygote. Single cell formed at conception; also called fertilized egg.