Transcript Genotype and Phenotype

Exploring Lifespan Development Third Edition  Laura E. Berk
Chapter 2
Genetic and
Environmental Foundations
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Exploring Lifespan Development Third Edition  Laura E. Berk
Genotype and Phenotype
Genotype
An individual’s
genetic
information
Phenotype
An individual’s
directly
observable
characteristics
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Exploring Lifespan Development Third Edition  Laura E. Berk
Genetic Foundations
Chromosomes
Rodlike structures within the
cells that store and transmit
genetic information
DNA
Deoxyribonucleic acid, the chemical
substance that makes up
chromosomes
Gene
Segment of DNA along the
length of the chromosome
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Exploring Lifespan Development Third Edition  Laura E. Berk
Mitosis and Meiosis
Mitosis
 Process by which
DNA duplicates
itself
 Produces new
body cells
containing the
same genetic
information
Meiosis
 Process by which
gametes (sex cells)
are formed
 Halves the number
of chromosomes
normally present
 Leads to genetic
variability
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Exploring Lifespan Development Third Edition  Laura E. Berk
Autosomes, Sex
Chromosomes, and Sex Cells
Autosomes
22 matching pairs
of chromosomes
Sex
chromosomes
23rd pair of chromosomes
(XX = female, XY = male)
Gametes
Sex cells: sperm and ovum
Zygote
Formed when sperm
and ovum unite
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Exploring Lifespan Development Third Edition  Laura E. Berk
Twins
Fraternal/Dizygotic
Result from release
and fertilization of two
ova
Identical/Monozygotic
Result when a single
zygote separates
to form two individuals
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Exploring Lifespan Development Third Edition  Laura E. Berk
Alleles
 Two forms of the same gene, one
inherited from each parent
 homozygous (both alleles are alike)
 heterozygous (alleles differ)
 Occur at the same place on both
chromosomes in a pair
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Exploring Lifespan Development Third Edition  Laura E. Berk
Dominant–Recessive
Inheritance
 Only the dominant allele affects
children’s phenotypic characteristics
 Carriers:
 heterozygous (have one recessive allele)
 can pass recessive trait to their children
 Many serious diseases are product of
recessive alleles
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Exploring Lifespan Development Third Edition  Laura E. Berk
Incomplete Dominance
 Both alleles are expressed in the
phenotype
 Possible results:
 combined trait
 trait that is intermediate between
the two
 Example: sickle cell anemia
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Exploring Lifespan Development Third Edition  Laura E. Berk
X-Linked Inheritance
Figure 2.4
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Exploring Lifespan Development Third Edition  Laura E. Berk
Genomic Imprinting, Mutation,
and Polygenic Inheritance
 Genomic imprinting:
 chemical marker activates one allele in a pair
 often temporary; may not occur in all individuals
 Mutation:
 sudden, permanent change in a segment of DNA
 may affect one or two genes, or many
 Polygenic inheritance:
 characteristics influenced by many genes
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Exploring Lifespan Development Third Edition  Laura E. Berk
Chromosomal Abnormalities
 Down syndrome: caused by problems
with 21st chromosome
 Sex chromosome abnormalities:
 caused by problems
with X or Y
chromosome
 often not recognized
until adolescence
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Exploring Lifespan Development Third Edition  Laura E. Berk
Reproductive Choices
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 Genetic
counseling
 Prenatal diagnosis
and fetal medicine
 Reproductive
technologies
 Adoption
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Exploring Lifespan Development Third Edition  Laura E. Berk
Reproductive Technologies
 Donor insemination
 In vitro fertilization
 Surrogate
motherhood
 New technologies
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Exploring Lifespan Development Third Edition  Laura E. Berk
Genetic Counseling
 Helps couples
 assess chances of hereditary disorders
 choose best course of action in view of risks
and family goals
 Recommended when
 couple has had difficulties bearing children
 known genetic problems exist
 woman is over 35
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Exploring Lifespan Development Third Edition  Laura E. Berk
Prenatal Diagnostic Methods
 Amniocentesis
 Chorionic villus
sampling
 Fetoscopy
 Ultrasound
 Maternal blood analysis
 Ultrafast magnetic resonance imaging
 Preimplantation genetic diagnosis
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Exploring Lifespan Development Third Edition  Laura E. Berk
Adoption
 Trends:
 international adoption
 adoption of older children
 adoption of children with
known developmental
problems
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 Children typically exhibit some difficulties,
but most fare well
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Exploring Lifespan Development Third Edition  Laura E. Berk
Environmental Contexts
for Development
 Family
 Socioeconomic
status and
family functioning
 Neighborhoods,
towns, and cities
 Cultural context
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Exploring Lifespan Development Third Edition  Laura E. Berk
Family Influences
on Development
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 Direct influences
 Indirect influences:
effects of third
parties
 Adaptation to
changes within
and outside
the family
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Exploring Lifespan Development Third Edition  Laura E. Berk
Socioeconomic Status (SES)
 Social status:
 years of education
 prestige of one’s job
and skill it requires
 Economic status:
income
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Socioeconomic Status
and Family Functioning
SES is linked to:
timing of marriage and parenthood
family size
values and expectations for children
parents’ education and economic security
communication and discipline styles
investment in children’s cognitive development
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Exploring Lifespan Development Third Edition  Laura E. Berk
Poverty
Who Is Poor?
 46 million Americans (15%) are poor
 Those hit hardest are:
 parents under age 25 with young children,
especially single mothers
 older adults who live alone,
especially women
 children, especially AfricanAmerican, Native-American,
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and Hispanic children
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Exploring Lifespan Development Third Edition  Laura E. Berk
Affluence
What Are the Risks of Affluence?
 Alcohol and drug use
 High levels of anxiety
and depression
 Unavailable parents:
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 lack of emotional
closeness and
supervision
 excessive demands
for achievement
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Exploring Lifespan Development Third Edition  Laura E. Berk
Beyond the Family
Benefits of Strong Community Ties
 Neighborhoods: resources and social ties
that promote development
 Towns and cities: mold
children’s and adults’
daily lives
 Small towns: promote
connection and
participation
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Exploring Lifespan Development Third Edition  Laura E. Berk
Cultural Context
 Cultural values and practices: shape daily
life within and outside the family
 Subcultures:
 cooperative family structures help protect
members from harmful effects of poverty
 collectivism vs. individualism
 Public policies: laws and programs
designed to improve current conditions
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Exploring Lifespan Development Third Edition  Laura E. Berk
Extended Families
 Three or more generations living together
 More common in many minority cultures
 Benefits:
 reduce stress of poverty
 provide assistance for
all generations
 create strong family bonds
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Exploring Lifespan Development Third Edition  Laura E. Berk
Individualistic and
Collectivist Societies
Individualistic
Collectivist
 People define
 People define
themselves as
themselves as part
separate entities
of a group
 Independent self  Interdependent self
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Exploring Lifespan Development Third Edition  Laura E. Berk
Indicators of Children’s
Health and Well-Being
Table 2.3
(Sources: Canada Campaign 2000, 2009; OECD 2010; U.S. Census Bureau, 2012; U.S. Department of Education, 2012.)
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Exploring Lifespan Development Third Edition  Laura E. Berk
Percentage of
Older Adults
Living in
Poverty
Figure 2.5
(Adapted from Luxembourg Income Study, 2011.)
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Exploring Lifespan Development Third Edition  Laura E. Berk
Behavioral Genetics
How Much Does Heredity
Contribute to Behavior?
Heritability Estimates
 Obtained from kinship studies
 Provide an estimate of proportion of
individual differences in a trait
attributable to heredity
 Range from 0 to 1.00
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Exploring Lifespan Development Third Edition  Laura E. Berk
Gene–Environment Interaction
 Individuals respond differently to same
environment because of genetic makeup
 Similar responses can result from different
gene–environment combinations
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Exploring Lifespan Development Third Edition  Laura E. Berk
Gene–Environment Correlation
 Passive correlation
 Evocative correlation
 Active correlation: niche-picking
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Exploring Lifespan Development Third Edition  Laura E. Berk
Epigenesis
Development results from bidirectional
exchanges between heredity and all
levels of environment
 Genes affect behavior and experiences
 Experiences and behavior affect gene
expression
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Exploring Lifespan Development Third Edition  Laura E. Berk
The Epigenetic Framework
Figure 2.7
(Adapted from Gottlieb, 2007.)
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Exploring Lifespan Development Third Edition  Laura E. Berk
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