Understanding Pregnancy and Genetic Factors: A Comprehensive Guide

2. 4 Pregnancy

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 • DNAstore the genetic code • Chromosomescarry the DNA

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

8. Chromosomes and Genes • Chromosomes • 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 traitstypically 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 occurs when two or more babies develop in the same pregnancy Multiple 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 developmenttakes place between conception and birth • germinal stage • embryonic stage • fetal stage

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

16. Germinal Stage • Amnionis 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 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 Fetal Stage 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 calledfertilized egg.