Chapter 2: Genetic Foundations, Reproductive Technologies, Environmental Contributions, Gene-Environment Interactions Flashcards
Gregor Mendel
1822–1884
Crossed varieties of pea plants of the same species
Traits he chose included dominant allele
Quite bit of work…
¤ Counted all offspring of 28,000 pea plants
Mendel’s Pea Experiment
Each individual has two hereditary “elements”
When an individual’s alleles are different, one allele can dominate the other
Genetic and Environmental Forces
Genotype: genetic material an individual inherits
Phenotype: observable expression of the genotype
Environment: every aspect of the individual and his or her surroundings other than the genes themselves
Chromosomes are long threadlike molecules made up of 2 twisted strands of DNA
DNA contains all instructions involved in the formation and functioning of an organism
Sex Determination
Sex chromosomes determine and individual’s sex
¤ Females = XX
¤ Males = XY
Gametes are formed through meiosis, which halves the number of chromosomes normally present in body cells
¤ Sperm + Ovum = Zygote
Boy or Girl?
22 of the 23 pairs of chromosomes are =
autosomes
the 23rd pair = sex chromosomes
Does a X-bearing or Y-bearing
sperm fertilize the ovum?
This is what determines the sex of a child.
Multiple Births:
Twins
Fraternal Twins:
Also known as dizygotic twins, and the most common type of twins.
Resulting from 2 eggs being fertilized.
Identical Twins:
When the zygote that has started to replicate
separates into two clusters of cells, they
develop into 2 individuals.
Frequency of 1 in 330 births.
Genes come in pairs
—one from each parent
Some pairs of genes are identical (homozygous), while others are not (heterozygous)
A Mendelian distribution occurs when traits are controlled by a single allele.
Homozygous: alleles from parents are alike, and the child will display the inherited trait
Heterozygous: alleles from parents are different, and the child might display the inherited trait
Careirs
Heterozygous individuals
Phenylketornuria
Infants born with 2 recessive alleles are
affected
Without PAH enzyme, phenylalanine builds up to toxic levels
Incomplete Dominance Pattern
..
X-Linked Pattern
When a harmful allele is carried on the X
chromosome, X-linked inheritance applies
In females recessive alleles on the X chromosome can be suppressed a dominant allele on the other X
Females benefit from a greater variety of genes
¤ Rates of miscarriage, infant death, birth defects, behavior disorders, and learning disabilities are higher in boys
¤ Nature compensates = 106 boys born for every 100 girls
Genomic Imprinting
Chemical marker that activates either father’s or mother’s gene
Imprinted genes represent less than 1% of the
mammalian genome
Often temporary– may be erased in next generation
Helps us understand puzzling genetic patterns
https://www.youtube.com/watch?v=iH9xHCeXQxQ
Fragile X Syndrome
Most common inherited cause of Intellectual Development Disorder (IDD)
Abnormal repetition of a sequence of DNA bases occurs in a special spot on the X chromosome, damaging a particular gene
¤ Suffer from attention deficits and
30–35% display autism symptoms, anxiety
¤ Passed on from mother
Mutation
A sudden but permanent change in a segment of DNA
¤ Radiation = established cause
¤ Germline mutation = takes place in the cells that give rise to gametes
¤ Somatic mutation = normal body cells mutate (can occur any time in life)
– Genetic susceptibility that causes certain body cells to mutate easily in the presence of triggering events
Polygenic Inheritance
Many traits of interest involve many genes – Height – Intelligence – Infant temperament – Shyness
BIRTH DEFECTS
Birth defects are serious conditions that change the structure of one or more parts of the body
Nearly 120,000 babies are affected by birth defects each year
More than 4,000 different types
GENETIC COUNSELING
Process designed to help couples assess their chances of giving birth to a baby with a hereditary disorder
– Miscarriages
– Known genetic problems
– Delayed childbearing
PREVENTATIVE METHODS:
BEFORE CONCEPTION
Identify women or couples at risk.... – Family history – Medication. Accutane? – Exposure Consider getting tested to see if parents are carriers of disease – Cystic Fibrosis, Sickle Cell
POST-PREGNANCY GENETIC METHODS:
WHAT ARE THE OPTIONS?
Early screening and (if necessary) diagnostic testing
Decision must be made by the couple
Considerations:
– Terminate an abnormal fetus
– Gather as much information a possible in order to be prepared
– Make special arrangements for potentially high-risk pregnancy
SCREENING VS. DIAGNOSTIC TEST
Screening Test:
– Assesses an individual’s risk
– Identifies disease or defect using a variety of procedures
– Fewer number of procedures utilized, not as much risk involved
Diagnostic Test:
– Designed to identify a disease or defect
– Gives patient a yes/no answer
– More invasive procedures
SCREENING TEST OPTIONS
Ultrasound: high frequency sound waves beamed at the uterus
– Reflection reveals the size, shape, and placement of the fetus
– Fetal age, detection of multiple pregnancies, and gross physical defects
– Risk: Using 5 or more times might increase chances of low birth weight
Ultrafast fetal magnetic resonance imaging (MRI)
– Scanner magnetically records detailed pictures of fetal structure – Brain and other abnormalities are detected
– No evidence of risk
DIAGNOSTIC TESTING
If screen was abnormal, then the family is typically referred to a genetic counselor and diagnostic testing will be offered
Chrionic villus sampling: 9 weeks Amniocentesis: 14–15weeks
Fetoscopy: 15–18 weeks
CHRIONIC VILLUS SAMPLING
As early as 9 weeks from conception
Thin tube inserted into the uterus through the vagina
OR
Hollow needle inserted through abdominal wall
A sample of tissues are removed from the end of chorionic villi and examined for genetic defect
Can reveal whether child has cystic fibrosis or Down syndrome
1% risk of miscarriage (1 in 100)

AMNIOCENTESIS
Occurs at about 15 weeks after conception
Hollow needle inserted through the abdominal wall to obtain fluid in the uterus Cells examined for genetic defects Small risk of miscarriage: 1 in 200 Injury, infection, and preterm labor are rare
FETOSCOPY
Occurs at about 18 weeks
A small tube with a light source at one end is inserted into the uterus to inspect the fetus for defects
Also allows sample of fetal blood
Can also be used to perform procedures on the fetus during pregnancy
ADOPTION
Adoption might be a viable option for adults experiencing:
– Infertility
– Carrier of a genetic disorder
– Single
Adopted children are increased risk for learning and emotional difficulties compared to non-adopted children
REPRODUCTIVE TECHNOLOGIES
Donor insemination and in vitro fertilization.
Ethical concerns: post-menopausal childbearing, “designer babies”
Surrogate motherhood.
Ethical concerns: Exploitation of financially needy women, insecurity of surrogate’s own children
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
THE FAMILY
Bronfenbrenner’s Ecological Systems Theory
The family is one of the most influential parts of the Microsystem.
Family includes attachment to parents & siblings
Family context is where children learn
– language
– skills
– social & moral values of their culture
Warm, gratifying family ties foster physical & psychological health.
Isolation, alienation from family can potentially lead to developmental problems
Bronfenbrenner’s model considers the family a system with bidirectional influences.
CHILD PARENT
Direct Influences of the Family:
PARENTAL DISCIPLINE
With Firm but Warm Discipline, generally children tend to comply.
With Harsh & Impatient Discipline, Children tend to rebel.
The ultimate effect of parental discipline often depends on child and cultural characteristics
Children with difficult temperaments more vulnerable (van Zeijl et al.)
Perceived “normativeness” of the discipline, according to the child. (Landford et al., )
INDIRECT INFLUENCES:
WHAT IS COPARENTING?
Partners relate to one another in their parenting roles (Feinberg)
“Executive subsystem” of the family (Minuchin)
Provides safety, communicates clear & consistent standards, and models cooperation between parents (McHale)
CONCEPTUALIZING COPARENTING
Feinberg, 2003
1) Agreement/disagreement on childrearing
2) Division of labor
3) Support and Undermining (Teubert & Pinquart, 2010)
4) Joint management of family interactions
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
The Family’s Ability to Adapt to Change
The family system is constantly changing.
Not just the young child, but everyone changes.

As children age and search for independence, parents strive for togetherness.
As our nation changes, families have become even more diverse.
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
SOCIOECONOMIC STATUS (SES)
Social position and economic standing
SES combines 3 variables:
– Years of education
– Prestige of one’s job/skills, both of which measure social status
– Income, which measures economic status
SES is linked to timing of parenthood and family size
SOCIOECONOMIC STATUS (SES) TRENDS
Lower SES:
• Tend to marry earlier, and have more children.
• Emphasize external characteristics such as obedience, politeness, neatness, and cleanliness in child-rearing.
• Have less control over their work lives, and tend to use a “boss-like” mentality in raising children.
• Lower SES is not associated with enhanced cognitive and language development.
Higher SES:
• Tend to marry later, and have fewer children.
• Emphasize psychological traits such as curiosity, happiness, self-direction, and cognitive & social maturity.
• Have more control over work- related decisions, and transfer those skills to children.
• Tend to fare better educationally.
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
AFFLUENCE
More money does not mean better parenting.
When tracking the adjustment of youths growing up in wealthy suburbs, by the 7th grade many of those involved in the study showed serious problems.
Grades dropped, and those kids were more likely than low-SES kids to engage in alcohol & drugs.
Poorly adjusted affluent kids report less emotional closeness with parents.
Additionally, some affluent parents value achievement over character development.
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
POVERTY
13% (40 millions Americans) are affected by poverty
Nearly 8% of children live in deep poverty, which is rare compared to international averages.
Children of poverty are more likely than other children to suffer from lifelong poor physical health, deficits in cognitive/academic achievement, high school dropout, mental illness, impulsivity, aggression, and antisocial behavior.
Poverty is magnified among ethnic minorities and women.
For single mothers with preschool children, the poverty rate is 50%
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
HOMELESSNESS
On a given night, 350,000 people have no place to live.
Most homeless families consist of women with children under the age of 5.
Many homeless teens also also wander the streets with no place to live, and no school to attend.
With few resources and high levels of stress, homelessness does not favor positive child development.
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
Neighborhoods
Mesosystem and Exostystem
Have you ever watched HGTV when the couple is looking for a house/ neighborhood where they can raise kids?
What does that look like?
Lower SES families are more dependent on neighborhood resources (e.g. the Shoenbaum Family Center) due to transportation and time constraints.
The neediest children are often the ones who don’t consistently attend school or community-related activities.
Social Support in the Neighborhood:
• Parental self-worth
• Parental access to valuable information and services
• Child-rearing controls and role models
• Direct assistance with child rearing (“It takes a village…”)
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
Schools
A formal institution designed to transmit knowledge & skills that children need to become productive members of their society.
Schools differ: • Student body size • Number of kids per class • Space/time available for work/play • Educational philosophies  Students whose parents are involved in schooling tend to fare better in academic endeavors
Subcultures
Subcultures are groups of people whose beliefs differ from those of the larger culture.
Extended-Family Household
For example, extended-family households are not the norm in the American culture; however, they are paramount in the survival of some minorities.
Collectivist vs. Individualistic Societies
Collectivist = people define themselves as part of a group and stress group over individual goals (interdependent self).
Individualistic = people think of themselves as separate entities and are largely concerned with their own personal needs (independent self).
The US culture is individualistic.
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT
CULTURE: Public Policies
Laws and government programs designed to improve current conditions.
E.g., building more low-income housing due to a poor economy, or granting schools extra funds to promote reading achievement.
Public Health Care: Obama Care
Maternity & Paternity Leave
ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT:
Looking Toward the Future of Culture
Convention on the Rights of the Child:
A legal agreement among nations that commits each cooperating country to work toward guaranteeing environments that…
• Foster children’s development
• Protect children from harm
• Enhance community participation and self determination
BUT, in our individualistic society, people worry that this would put the burden of child-rearing on the state rather than the parents, so there is opposition to this legal agreement.
Behavioral Genetics
Attempts to answer the question of how much each factor contributes to differences.
Heritability estimates: measure the extent to which individual differences in complex traits in a specific population are due to genetic factors.
Kinship Studies: Compare characteristics of family members
Twin studies
• identical: 100% shared genes
• fraternal: 50% shared genes
Adoption studies.
Are children more similar to their adoptive or biological parents?
HOW DO GENES AND ENVIRONMENT WORK TOGETHER?
Gene-Environment Interaction:
Difference in response to environment based on genetic make-up.
GENE–ENVIRONMENT CORRELATION
Passive correlation – “no control”
Evocative correlation – elicit responses.
Active correlation – “actively” seek.
• Niche-picking:
https: //www. youtube. com/watch? v=1gwnzW4jOMI

ENVIRONMENTAL INFLUENCES ON GENE EXPRESSION
Gene–environment Correlation is viewed as driven by genetics.
• Many researchers take issue with the supremacy of heredity.
• Bidirectional influences between heredity and environment
Adults can uncouple unfavorable gene–environment correlations.
THE EPIGENETIC FRAMEWORK
Development resulting from ongoing Bidirectional Exchanges between gene expression, behavior, and environment.
Protein-Coding Genes
directly affect the body’s characteristics
Regulator Genes
modify the instructions given by protein-coding genes
Bronfenbrenner’s ecological systems theory
an attempt to explain how children grow and develop.
It is made up of steadily larger groups of influence, ultimately culminating with all the experiences of a child’s entire lifetime.
The smallest, closest level is the microsystem. This is the most immediate and direct influence on the child’s development, and includes such factors as family, school, religious institutions, neighbors and peers.
Beyond that is the mesosystem. This represents the influence of two microsystems interacting. This can include such things as friends interacting with parents, parents interacting with teachers, teachers interacting with friends and so on.
After that is the exosystem. This is the environmental settings that a child is not actively involved in, but is influenced by. An example would be a parent getting a promotion that rewards him with higher pay, but involves longer work hours.
The macrosystem serves as the overall definition of the child’s culture. This includes the political & social beliefs of the culture, defined by being part of a group with a common heritage or identity.
Last is the chronosystem. This system includes major life transitions, environmental events and historical events that occur during development. The specific incidents tend to change or transition how the child interacts with all the rest. Moving to another city is one example, as is the first moon landing being televised.
Methylation
DNA methylation plays a role in the long-term silencing of transcription and in heterochromatin formation.
As an epigenetic modification, DNA methylation permits these silenced states to be inherited throughout cellular divisions.
