1. Child Development, 3/e by Robert Feldman
Chapter 3
The Start of Life: Genetics and Prenatal Development
Created by Barbara H. Bratsch

2. What is our basic genetic endowment, and how can
human development go awry?
How do the environment and genetics work together
to determine human characteristics?
Which human characteristics are significantly influenced by heredity?
What happens during the prenatal stages of development?
What are the threats to the fetal environment, and what
can be done about them?

3. Genetics
Our genetic code is stored in our genes. All genes are composed of DNA (deoxyribonucleic acid) that determines the nature of every cell in our bodies and how they will function.
46 Chromosomes are organized into 23 pairs of DNA portions
A zygote is a new cell formed by fertilization
Gametes are sex cells from the mother and father that form a new cell at conception

4. Genetics

5. Multiple Births
Monozygotic twins are genetically identical and formed by one fertilized ovum that splits
Dizygotic twins are formed when two separate ova are fertilized by two separate sperm at the same time

7. How are boys and girls made?
Females are made by the 23rd pair of chromosomes that consist of XX ( an X chromosome from the mother and an X chromosome from the father)
Males are made by the 23rd pair of chromosomes and consist of an XY (an X chromosome from the mother and a Y chromosome by the father

8. Making a Girl
Making a Boy

9. Basics of Genetics
Dominant trait – one trait expressed when two competing traits are expressed
Recessive trait – a trait present in an organism but not expressed
Genotype – the underlying combination of genetic information (not outwardly visible)
Phenotype – an observable trait
Homozygous - Similar genes for a given trait that are inherited from parents
Heterozygous – Different forms of a gene for a given trait inherited from parents

10. Phenylketonuria (PKU) – an inherited disorder in which a child
is unable to make use of phenylalanine, an essential amino acid
present in proteins found in milk and other levels. If left untreated,
PKU allows phenylalanine to build up to toxic levels and the
result can be brain damage and mental retardation

13. Polygenic inheritance
Gregor Mendel
pioneered experiments on pea plants that provided the foundation for the study of genetics
Polygenic inheritance
a combination of multiple gene pairs is responsible for production of a particular trait
X-linked genes
are recessive and located only on the X chromosome.
Hemophilia is produced by X-linked genes

14. The Human Genome
Completed in early 2001, the mapping of the specific sequence of genes on each chromosome was one of the most important moments in the history of genetics
Behavioral Genetics studies the effects of heredity on behavior

16. Inherited and genetic disorders include:
PKU
Down syndrome
Fragile X syndrome
Sickle-cell anemia
Tay-Sachs disease
Klinefelter’s syndrome

17. Genetic Counseling focuses on helping people deal with issues related to inherited disorders
Prenatal testing includes an amniocentesis in which fetal cells are drawn out of the amniotic sac before a child is born
Chorionic villus sampling (CVS) can be performed even earlier at 8-11 weeks and involves sampling of hairlike materials that surround an embryo
Ultrasound sonography – high frequency sound waves are used to produce an image of the unborn child. This is less risky and invasive than amniocentesis or CVS

18. Heredity Vs. Environment
Multifactorial transmission states that many traits are a combination of both genetic and environmental factors

19. How to Answer the Nature-Nurture Riddle
Animal studies – breeding genetically similar animals and determining various environmental influences
Human studies – studies of monozygotic and dizygotic twins have produced data around genetic similarities, dissimilarities and environment

21. Genetics and IQ Genetics plays a significant role in intelligence
The closer the genetic link between two individuals, the greater the correspondence of their overall IQ scores

22. Genetics, Environment, and Personality
These traits are among the personality factors that are related
most closely to genetic factors

23. Genetics, Environment, and Psychological Disorders

24. Schizophrenia has clear
genetic components.
The closer the genetic
links between someone
with schizophrenia and
another family member,
the more likely it is that
the other person will also
develop schizophrenia

25. Can Genes Influence the Environment?
Active genotype-environment effects – Situations in which children focus on aspects of their environment that are most congruent with their genetically determined abilities
Passive genotype-environment effects – Situations in which parents’ genes are associated with the environment in which children are raised
Evocative genotype-environment effects – Situations in which a child’s genes elicit a particular type of environment

26. Prenatal Growth and Change
Fertilization, or conception, is the joining of sperm and ovum to create the single-cell zygote
Female and Male Sex Organs

27. Giving Nature a Boost
Infertility – inability to conceive after months of trying to become pregnant
Artificial insemination – fertilization process in which a man’s sperm is placed directly in a woman’s vagina by a physician
In vitro fertilization (IVF) – a procedure in which a woman’s ova are removed from her ovaries and a man’s sperm are used to fertilize the ova in the lab
Surrogate mother is a woman who agrees to carry a child to term if the mother who provides the donor eggs is unable to conceive

28. Stages of Prenatal Development: The Onset of Development
Germinal - Fertilization to 2 weeks
Embryonic - 2 weeks to 8 weeks
Fetal stage - 8 weeks to birth

30. voluntary termination of a pregnancy
Miscarriage
spontaneous abortion
Abortion
voluntary termination of a pregnancy

31. Threats to Development
Teratogen environmental agent such as a drug, chemical, virus, or other factor that produces a birth defect

32. Threats to Development
Mother’s diet
Mother’s age
Mother’s prenatal support
Mother’s illness
Mother’s drug use
Mother’s use of alcohol, tobacco, and caffeine
Father factors