1. Child Development A Cultural Approach Chapter 2 Genetics and
Prenatal Development
Copyright © 2017, 2013 Pearson Education, Inc. All Rights Reserved

2. Learning Objectives (1 of 4)
2.1 Distinguish between genotype and phenotype and identify the different forms of genetic inheritance. 2.2 Describe the sex chromosomes and identify what makes them different from other chromosomes. 2.3 Explain how behavior geneticists use heritability estimates and concordance rates in their research. 2.4 Describe how the concept of epigenesis frames gene–environment interactions, and connect epigenesis to the concept of reaction range.

3. Learning Objectives (2 of 4)
2.5 Explain how the theory of genotype environment effects casts new light on the old nature–nurture debate. 2.6 Outline the process of meiosis in the formation of reproductive cells. 2.7 Describe the process of fertilization and conception. 2.8 List the major causes and treatments for infertility, and describe how infertility is viewed in different cultures.

4. Learning Objectives (3 of 4)
2.9 Describe the structures that form during the germinal period Outline the major milestones of the embryonic period Describe the major milestones of the fetal period and identify when viability occurs Compare and contrast prenatal care in traditional cultures and developed countries Identify the major teratogens in developing countries and developed countries.

5. Learning Objectives (4 of 4)
2.14 Explain how chromosomal disorders occur Describe causes and symptoms of some common genetic disorders Describe the three main techniques of prenatal diagnosis Explain who is likely to seek genetic counseling and for what purpose.

6. Genetic Influences on Development

7. Genetic Basics: Expression of Traits (1 of 3)
Chromosomes-structure containing genes
DNA-stores and transfers genetic material
Gene-segment of DNA containing coded instructions
Genome-entire store of hereditary information

8. Genetic Basics: Expression of Traits (2 of 3)
Genotype – the totality of an individual’s genes
Phenotype – actual characteristics
This is what is seen or observed and can include a wide range of things
Website shows impact of environment on physical appearance on genetically identical twins.

9. Genetic Basics: Expression of Traits (3 of 3)
Dominant genes – expressed characteristics
Recessive genes – not expressed, although it is a part of the genotype (genetic background)
Allele – alternate form of a gene
Dominant–recessive inheritance – a pair of chromosomes contains one dominant and one recessive gene
This can be used to explain curly and straight hair for SINGLE Dominant Genes.

10. Figure 2.1 The Human Genome
The 46 chromosomes in the human genome are organized into 23 pairs. This is the genome of a female; in a male the 23rd pair would be XY rather than XX

11. Table 2.1 Traits with Single-Gene Dominant–Recessive Inheritance
Curly hair
Straight hair
Dark hair
Blonde hair
Facial dimples
No dimples
Normal hearing
Deafness (some forms)
Normal vision
Nearsighted vision
Freckles
No freckles
Unattached ear lobe
Attached ear lobe
Can roll tongue in U-shape
Cannot roll tongue in U-shape

12. Genetic Basics: The Sex Chromosomes
The 23rd pair of chromosomes determines male or female
Males more vulnerable to X-linked recessive disorders
X-linked inheritance

13. Figure 2.3 X-Linked Inheritance in Hemophilia
Why are males more vulnerable to recessive disorders carried on the X chromosome?

14. Genetic Basics: Genes and the Environment (1 of 2)
Behavior genetics
Estimating influence of genes and environment on development
Utilize twins to understand importance of genetics and tease out environment effects
Monozygotic (MZ) twins – same genotype
Dizygotic (DZ) twins – two ova fertilized by sperm
Since identical twins share identical genes and fraternal twins only about 40-60%, by comparing similarities and differences one can get an indication of the role of genes on certain traits.
Studying adopted children can also be beneficial.

15. Genetic Basics: Genes and the Environment (2 of 2)
Heritability
An estimate of the extent to which genes are responsible for differences among persons within a specific population
Concordance rates
Percentage that indicates degree of similarity in phenotype among pairs of family members
Heritability ranges from 0-1 and provides information about some degree of impact of genes and environment.
Concordance rates can indicate some degree of genetic contribution of a condition.

16. Epigenesis and Reaction Ranges
Epigenesis – the continuous bidirectional interactions between genes and environment
Genetic activity responds constantly to environmental influences
Genes establish a reaction range of potential expression and environment determines where phenotype will fall

17. Genotype and Environment Effects
Genotype-environment effects
Passive genotype
Results from the fact that in a biological family, parents provide both genes and environment to their children
Evocative genotype
Results when a person’s inherited characteristics evoke responses from others in the environment
Active genotype
Results when people seek out environments that correspond to their genotypic characteristics

18. Sperm and Egg Formation
Gametes are reproductive cells (sperm and ovum)
Mitosis is normal cell duplication and division with 46 chromosomes
Meiosis is duplication and division with 46 chromosomes but in the process a division occurs to allow only 23 chromosomes (ovum and sperm cells)

19. Figure 2.4 The Creation of Gametes Through Meiosis
Define the major terms Gametes which are reproductive cells (sperm and ovum).
Use slide and figure to visually demonstrate meiosis as a variation of mitosis.
Mitosis is normal cell duplication and division with 46 chromosomes.
Meiosis is duplication and division with 46 chromosomes but in the process a division occurs to allow only 23 chromosomes (ovum and sperm cells).
How does meiosis differ from mitosis?

20. Conception
For conception to occur there must be a released ovum and a sperm
Ovulation releases the ovum, and if sperm is available, fertilization can occur
There is only about a 24 hour window for fertilization to take place after ovum enters the fallopian tube.
Sperm can last 2-5 days in a woman’s body to try to fertilize the ovum.
In some cases instead of one ovum being released, two are released which, if fertilized, can lead to fraternal or dizygotic twins. (Mention ethnic variation here as well.)

21. Figure 2.5 Ovulation Process
The two ovaries alternate ovulation in each monthly cycle.

22. Infertility Causes For men three main causes For women many causes
Too few sperm
Quality of sperm
Low motility
For women many causes
One is ovulation

23. Figure 2.6 Fertility and Maternal Age
Why does fertility decline after the mid-20s?

24. Infertility Treatments
Many treatments utilize assisted reproductive technologies (ART)
Artificial insemination
Injects sperm into woman’s uterus
Fertility drugs
Mimic hormones involved in ovulation
In-vitro fertilization
Ova removed and fertilized outside the womb then placed into uterus
Specific information about multiples with Insemination and fertility drugs to match the photo.

25. Infertility Worldwide
Cultural differences exist on how infertility is viewed
In the West there may be a sense of sadness or loss as well as marital strain
About half of all couples say it has made marriage stronger
Outside of the West, can be deeply stigmatizing, especially for women

26. Figure 2.7 Milestones of Prenatal Development

27. The Germinal Period (First 2 Weeks)
During the travel from the fallopian tube to the uterus cell division is taking place
Blastocyst – ball of about 100 cells formed by 1 week after conception
Trophoblast – outer layer of cell that will form structures that nourish and protect embryo
Amnion – fluid-filled membrane in the womb
Embryonic disk – inner layer of cells which will form embryo
Describe cell division as well as the blastocyst, trophoblast and what makes up the embryonic disk.
Highlight that the trophoblast will differentiate and develops the amnion.
Other key structures to mention are placenta and the umbilical cord.

28. The Embryonic Period: Weeks 3 to 8 (1 of 2)
Key Developments
Embryonic layers
Ectoderm – becomes skin, hair, nails, sensory organs, and the nervous system
Mesoderm – becomes the muscles, bones, reproductive system, and the circulatory system
Endoderm – becomes the digestive system and respiratory system
Highlight development of each part and what each will become according to the text.

29. The Embryonic Period: Weeks 3 to 8 (2 of 2)
Key organs and structures are forming, including:
Neural tube develops by week 3
Eyes, nose, mouth, and heartbeat by week 4
Buds that will be arms and legs start to develop in week 5
Liver, digestive system, and heart’s separate chambers by week 8
Identify specific week for each structure.

30. The Fetal Period (Week 9 to Birth)
The longest period of prenatal development
Genitals develop by month 3
Movement can be felt by month 4
Breathes, hiccups, and responds to sound by the end of month 6
Main impediment to viability is lung development
Identify specific timeline development as important for the instructor and the class.
Viability is important to mention.
Interesting question to ask class is when fetus may feel pain. Or when they think there is brain activity.

31. Prenatal Care ( 1 of 2)
Prenatal beliefs are impacted by generational wisdom of the time
These beliefs can include
Avoiding wine (Beng)
Specific types of meat (Beng)
Certain types of hot or cold food (Bali)
Witches (Bali)
A mix of practical and cultural ideas for prenatal care
Identify specific cultures for each belief system.

32. Prenatal Care: (2 of 2)
Developing countries have developed specific beliefs as well
These scientific beliefs include
Women typically gain pounds
Women should receive regular evaluations
Current care can vary by ethnicity and SES
Developing world less likely to receive prenatal care

33. Map 2.1 Ethnic Variations in Prenatal Care within the United States
How does prenatal care differ for White women compared with other ethnic groups? What economic factors might account for these variations?

34. Teratogens (1 of 3)
Teratogens are environmental and bodily conditions that could be harmful
They can include tobacco, alcohol, prescription medications, and other drugs
The physical environment could also be a teratogen due to malnutrition or exposure to hazardous chemicals

35. Teratogens (2 of 3)
Malnutrition is the most common worldwide teratogen
Eating healthy diets is recommended but not likely in developing countries
Living in rural areas could also impact prenatal health
Folic acid can reduce incidences of anencephaly and spina bifida

36. Teratogens (3 of 3) Two key vitamins are iodine and iron
Iodine deficiency tends to be a bigger issue in developing countries
Iron is necessary for a healthy pregnancy
It is important for women to drink fluids and expect increase in caloric intake of about calories.

37. Figure 2.8 Timing of Teratogens
Vulnerability to teratogens is greatest in the embryonic period.

38. Teratogens: Infectious Diseases (1 of 2)
Rubella (German measles)
Exposure during embryonic stage can lead to heart abnormalities and mental retardation
Exposure during the fetal stage can lead to hearing problems and low birth weight
Vaccination can help but rubella remains widespread in less developed countries

39. Teratogens: Infectious Diseases (2 of 2)
AIDS (Acquired Immune Deficiency Syndrome)
Three strategies can help prevent transmission
Effective medicines
Cesarean sections for AIDS-infected moms
Infant formula in place of breast-feeding
Good idea to have a discussion about which strategies could be employed in developing world that could be more effective.
Possibly relate this to malnutrition as well especially regarding strategy number 3.

40. Teratogens: Alcohol Widespread damage in developed countries
Fetal alcohol spectrum disorder
Includes facial deformities, heart problems, misshapen limbs, and a variety of cognitive problems
Increased effects as child develops

41. Teratogens: Nicotine
Maternal smoking increases risk of miscarriages, premature birth, and low birth weight
Infant effects include difficulty breathing and impaired heart functioning
Childhood effects include poorer language skills, attention and memory problems, and behavior problems
Secondhand smoke by fathers is also detrimental

42. Other Teratogens Alcohol and tobacco are common in developed countries
Recreational psychoactive drugs cause physical, cognitive and behavioral problems
Marijuana affects development of the brain and CNS
Cocaine can result in low birth weight
Heroin can lead to painful withdrawal
Prescription drugs can be damaging

43. Pregnancy Problems

44. Chromosomal Disorders
Chromosomal disorders can occur because of an issue during meiosis
This may cause too many or too few chromosomes in the cells of the zygote
Two types of chromosomal disorders are:
Sex chromosome disorders
Disorder on the 21st chromosome (Down syndrome)

45. Sex Chromosome Disorders
Sex chromosomal disorder can result from an extra X, an extra Y, or only an X and no second chromosome
Common consequences of sex chromosome disorders include:
Cognitive deficit
Abnormality in reproductive system at puberty

46. Down Syndrome Trisomy-21
Identifiable by physical characteristics
Cognitive deficits
Speech problems
Mental retardation
Social development varies
Lower life expectancy
Mention specific physical and social development.

47. Parental Age and Chromosomal Disorder
Chromosomal disorders tend to NOT be passed from parent to child
Relationship between maternal age and chromosomal disorders
There may be a relationship between a father’s age and chromosomal disorders but it isn’t as clear

48. Figure 2.9 Down Syndrome and Maternal Age
Why does the risk rise so steeply after age 40?

49. Prenatal Diagnosis Ultrasounds – uses high frequency sound waves
Amniocentesis – utilizes amniotic fluid
15 to 20 weeks into pregnancy
Chorionic villus sampling – utilizes cells from forming umbilical cord
5 to 10 weeks into pregnancy
Be sure to identify why amniocentesis may be preferred over CVS and possible risks with each.

50. Genetic Counseling
Before having children some may seek out genetic counseling
Inherited genetic condition
Couples with history of miscarriage or infertility
Older couples (women over 35, men over 40)