Child Psychology Ch. 2-4

- Heredity & Consumption, Prenatal Development, Birth & the Newborn Baby

Heredity

• Based on biological transmission of traits and characteristics from one generation to another

Genetics

• Branch of biology that studies heredity

Genetic (Inherited) Influences

• physical traits

• Intelligence, emotional, and personality traits

• Behavioral traits and psychological issues

Chromosomes

• Found in cells

• 23 pairs of rod-shaped structures

Genes

• Segments within chromosomes

• Regulate development of traits

  • transmitted by single gene or may be polygenic

• 20,000 to 25,000 genes in every cell

DNA

• Large strands make up genes

• double spiral (helix)

• Composed of phosphate and simple sugar

• Base pairs adenine with thymine (A - T) or cytosine with guanine (C - G)

Mitosis

• Cell division by which growth occurs and tissues are replaced

• Stands of DNA break apart, duplicate, and are rebuilt

• Result is identical copies of DNA strand

  • mutations are the exception

Meiosis

• Cell division by which sperm and ova are produced

• 23 chromosomes pairs divide

• Result is a new cell with only 23 chromosomes

  • 22 pairs are autosomes

  • 23rd pair are sex chromosomes

    • determines sex: X from mother and X or Y from father

Monozygotic (Identical) Twins (MZ)

• Derived from a single zygote that has split in two

Dizygotic (Fraternal) Twins (DZ)

• Derived fro, two zygotes

• Share 50% of genetic material

Probability of twins increases:

• Maternal age - less regular ovulation

• Use of fertility drugs

What are Dominant and Recessive Traits?

Traits are determined by pairs of genes

• each member of pair is an allele

Homozygous

• Both alleles for a traits are the same

Heterozygous

• Alleles for a trait are different

Gregor Mendel

• Established the laws of heredity

Averaging

• effects of both alleles are shown

• incomplete dominance or codominance

law of Dominance

• Dominant allele paired with recessive allele

  • Dominant allele appears in offspring

Chromosomes or genetic abnormalities

• Occur in outcomes or sex chromosomes

• May be caused by a single gene or combinations

• Multifactorial problems

Chromosomal Abnormalities: Down Syndrome

• Cause: extra chromosomes on 21st pair

• Probability increases with increased age of parent

• Characteristics:

  • facial features

  • deficits in cognitive, language, and motor development

• Adjustment problems

Male with extra sex chromosome

• XYY: extra Y chromosome

• XXY: Klinefelter syndrome

Female with abnormal number of sex chromosomes

• X: Turner syndrome

• XXX: Triple X syndrome

Genetic Abnormalities

• Phenylketonuria (PKU)

• Huntington Disease

• Sickle-cell anemia

• Tay-sachs disease

• Cystic fibrosis

Carried on X sex chromosome

• Hemophilia

• Duchenne muscular dystrophy

• Diabetes

• Color blindess

• Some type of night blinds

Genetic Counseling

• Addresses probability of genetic abnormalities

• Information about couple’s genetic heritage

• Prenatal testing

  • Amniocentesis

  • Chronic villus sampling (CVS)

  • Ultrasound

  • Blood tests

Amniocentesis

• usually performed on mother about 14-16 wks after conception

• Can detect more than 100 chromosomal and genetic abnormalities in fetus

• Indicates the sex of the baby

• Some risk of miscarriage

• Improved ultrasound and blood tests is reducing use of amniocentesis

Chronic Villus Sampling (CVS)

• Can diagnosis abnormalities earlier than amniocentesis

• Equal or slightly higher risk of miscarriage, compared to amniocentesis

Ultrasound

• Sonogram “picture” of fetus

• Used to track fetus growth and to determine age, sex, and structural abnormalities

Blood tests

• Can reveal presence of recessive genes in parents

• Alpha-Fetoprotein (AFP) assay

Reaction Range

• Range of possibilities for the expression of the trait

  • Genotypes

  • Phenotypes

Genotypes

• Sets of traits inherited from parents

Phenotypes

• Actual sets of traits

• Product of genetic and environmental influences

Canalization

• Environmental influences on genotype within reaction range

  • Canalization = sequence of development is invariant

    • Infant motor development

  • Less canalization

    • Intelligence

    • Personality

Genetic - Environmental Correlation

• Passive Correlation

• Evocative Correlation

• Active Correlation

Passive Correlation

• Environment that child is placed into

Evocative Correlation

• Child’s genotype elicits responses

Active Correlation

• Environment child chooses

Epigenetic framework

• Development reflects the continual bidirectional exchanges between genetics and environmental influences

Kinship Studies

• Genetic closeness of relatives

Twin Studies

• Monozygotic twins share 100% of genes

• Dizygotic twins share 50% of genes (same as siblings)

• Reared together versus reared apart

Conception

• ovarian follicle ruptures releasing the egg

• Hundreds of millions of sperm are ejaculated

  • only a few thousands survive through the cervix

  • a few hundred bombard the ovum in the fallopian

• Sperm and ovum unite

Ova

• Begin to mature at puberty

• Monthly release of mature egg into fallopian tube

• Egg is propelled by cilia and, perhaps, by contractions in the wall of the fallopian tube

• If not fertilized, egg is discharged along the endometrium

Sperm Cells

• Each contains 46 chromosomes, including one X and one Y

• Self propelled and smaller than ova

• Sperm with Y chromosome swim faster than sperm with X chromosomes

  • more boys are conceived than girls

• From 200 to 400 million in ejaculate; only 1 in 1000 arrive in vicinity of ovum

• Attracted by chemical odor secreted by ova

• Sperm must penetrate gelatinous layer around ova

What are causes of Infertility among men?

• low sperm count

• Deformed sperm

• Diseases

• Injury of testes

• Autoimmune responses

  • Causes: Genetic factors, environmental poisons, diabetes, STI’s, overheating tests, pressure to tests, aging, and drugs

What are causes of Infertility among females?

• Irregular or absence of ovulation

  • fertility drugs are used to cause women to ovulate

• Declining hormone levels due to aging

• Endometriosis

• Obstructions or malfunctions of reproductive tract

• Causes:

  • Hormone irregularities

  • Stress

  • Malnutrition

  • Infections that produce obstructions, as from scarring

    • Pelvic inflammatory disease

How are couples with fertility problems assisted?

• Artificial Insemination

• In Vitro Fertilization

• Donor IVF

• Surrogate Mothers

• Adoption

Artificial Insemination

• Sperm injected into mother’s uterus

In Vitro Fertilization

• Ova and sperm are fertilized, then implanted in mother’s uterus

Donor IVF

• Ovum harvested from donor woman; fertilized in vitro and implanted in recipient’s uterus

• Embryonic transplant

Surrogate Mothers

• “Substitute” who carries a baby to term for another woman

• Ethical and legal risk because the surrogate mother may not want to give up the baby

Adoption

• greater diversity of adopted children and adoptive parents

• Consideration of adopted children needs

• Relinquishing mothers also experience effects