Transcript Biological and Environmental Factors

Biological and
Environmental Factors
Chapter 2 Summary Notes
* Notes for educational
purposes only-use with
course textbook
Overview
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Bases for Genetic
make-up
Choices in
Reproduction
Development and the
Family
The Relationship
Between Heredity and
Environment
Genetics
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Heredity and environment are foundations
of development
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Genotype- genetic make-up
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Phenotype- observable characteristics
Genetic Code
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Body composed of
over a trillion cells
Center of cell is
nucleus which
contains
chromosomes
Chromosomes- store
and transmit genetic
information
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DNA- double strain
molecules that
makeup
chromosomes and
contain genetic code
Gene- segment of
DNA molecule
Mitosis- cell
duplication (each cell
receives exact copy of
genetic code)
Sex Cells
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Gametes-sex cells (sperm 23 chromosomes and
ovum 23 chromosomes)
Meiosis- cell division that forms gametes
No two gametes will ever be the same
Zygote- sperm and ovum unite at conception 46
Chromosomes
Sperm are produced continuously; all ova are
present at birth
22 autosomes; 1 sex chromosome; xy- male; xxfemale
Mulitiple Births
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Twins
– Fraternal (dizygotic) most common type
• Two ova are fertilized; genetic makeup similar to ordinary
siblings
– Identical (monozygotic) one zygote separates into
two clusters of cells that become two individuals;
same genetic makeup
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Triplets (3); Quadurplets (4); Quintuplets (5);
Sextuplets (6), Septuplets (7)
Increase in Multiple Births?!
Increase Facts
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1978-1988- 17% single births; 33% twin
births; 101% triplets and higher
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Trends in family planning and advances
in reproductive technology assist in
increase
Patterns of Genetic Inheritance
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2 forms of genes
occur at the same
place on the
autosome- father &
mother
Homozygous- alike
genes from both
parents (inherited
trait)
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Heterozygousdifferent genes from
both parentsrelationship of genes
determine trait that
will appear.
Dominant- recessive
inheritance- a pattern
one gene’s influence
is exhibited
(heterozygous)
Dominant- Recessive Terms
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Dominant- expressed gene
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Recessive- not expressed
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Carrier- heterzygous; pass recessive
gene to his/her children
Diseases that are result of
recessive genes
PKU
 Cystic Fibrosis
 Sickle Cell Anemia
 Tay-Sachs disease
 Hemophilia
(Page 50 in text)
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Who is more at risk ( Multiple
Births)?
Older women
 Women with more children
 Fertility drug clients
 African American Women (fraternal
twins)
 Tall, normal, or overweight (fraternal
twins)
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Patterns of Genetic Inheritance
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2 forms of each gene
occur at the same
place on the
autosomes- 1 mother;
1 father
Homozygous- both
genes are alike
Heterozygousrelationship between
genes determine trait
that will appear
Dominant- Recessive Inheritance
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A pattern in a
 Carrierheterozygous
heterozygous
relationship only one
relationship passes
gene’s influence is
recessive gene
exhibited
 Dominantexpressed
 Recessive- not
expressed
Diseases with recessive trait
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PKU
 Sickle Cell Anemia
 Tay-Sachs Disease
 Cystic Fibrosis
 Cooley’s Anemia
(Pages 50-51 in text)
 Genetically linked
illnesses
Codominance
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Codominance
– Both genes influence the person’s
charateristics
– Sickle Cell Anemia
Mutation
Change in DNA segment
 Harmful genes
 By chance
 Or by hazardous substances in the
environment
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X-linked inheritance- recessive gene is
carried on the X-Chromosome
– Males more likely to be affected (sex
chromosomes don’t match)
– Hemophilia
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Males may be at a disadvantage in other
areas not necessary linked to X-linked
inheritance- miscarriage and infant deaths
 Learning disability, behavior disorders mental
retardation (Halpern, 1997)
Genetic Imprinting
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Pattern of inheritance where some
genes are chemically marked in such a
way that one pair is activated regardless
of its makeup
– Diabetes in the father
– Asthma in the mother
– Fragile X syndrome (MR, autism) mother
Chromosomal Abnormalities
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Defect occurs during meiosis (DNA)
 Down Syndrome
– 21st chromosome contains extra genetic material
– Physical features- short, stocky build, flatten face,
protruding tongue, almond shape eyes, possible
heart and intestinal defects, speech problems,
delayed motor and cognitive defects
– Increase chances of having a baby with Down
Syndrome with age of mother
Abnormalities in Sex
Chromosomes
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Either the presence of extra chromosome or
the lack of one of the X chromosomes
 Triple X syndrome (XXX)- girl- verbal
difficulties
 Turner syndrome- (XO) missing X-spatial
relationships
 Klinefelter syndrome (XXY)- verbal difficulties
Reproductive Choices
Genetic Counseling- communication
about chances of couples having a baby
with hereditary disorders
 Prenatal diagnostic methods
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– Page 55 in text
Other choices
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Adoption
 In vitro fertilization
 Fertility drugs
Environmental Factors
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Family
Friends
School
Experiences
Society
Culture
Social Systems Perspective
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Family as complex system
– Behavior of family affects those of other family
members
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Influence is directed or indirect- third party
can support or undermine other family
relationships
 Family dynamic ever- changing system
 Can be modified by important life events
 Development status of each family member
and historical time period effects families
Socioeconomic Status (SES) and
Family Functioning
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3 variables
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Years of education
Job prestige and skills required
Income
SES may affect differences in child-rearing
practices
– Lower- SES family may focus on external
characteristics (obedience, neatness, cleanliness)
– Higher SES focus on psychological traits-curiosity
• Happiness, and self- direction
• As early as 2nd year of life SES affects with cognitive and
language development
Impact of Poverty
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36 million people
 14% of the population
 Hardest hit
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Parents under 25 with young children
Elderly who live alone
Ethnic minorities
Women
20% children; 32% Hispanic; 40% African
American; 32% Native American
More on Poverty
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Parents in poverty
– Experience hassles and crises affecting childrearing ability
– Poor housing and dangerous neighborhoods
increase stress levels of poor families
– Homeless children suffer from developmental
delays, emotional stress, health problems, school
absenteeism, poor academic performance
Beyond the Family
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Community impact on family
– Child abuse and neglect are greatest
• With weak family and community ties
• Family stress and child adjustment problems are reduced
with strong family ties
• Safe neighborhoods and communities with physical and
social support
• Influence well-being in adulthood
• Smaller towns- fewer culture experiences than citiesgreater community involvement and safer environments
Culture
Cultures shape family interactions and
community settings beyond the home
 American cultural values- independence
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– Self-reliance, privacy
– Subcultures- groups of people with beliefs
and customs that differ from those of the
larger culture
African American Extended
Family
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Extended family- 3 or more generations live
together
Survival poverty, prejudice and economic
deprivation (McAdoo)
More kin visits
Reduce stress
Grandmothers are significant
Elderly have higher life satisfaction
Strong Family bonds, child development
Survival for future generations
Individualism vs. Collectivism
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Individualism societies- people think of
themselves as separate entities;
concerned with their own goals (US)
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Collectivism societies- people define
themselves as part of a group and
stress group over individual goals