Biological and Environmental Foundations - Ashton Southard

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Biological and Environmental Foundations - Ashton Southard Powered By Docstoc
					Biological and Environmental
           Chapter 2
Genotypes and Phenotypes
 Genotype
  Individuals’ unique genetic makeup
 Phenotype
  Directly observable characteristics
    Example: hair color, eye color, height, etc.
Genetic Foundations
 Chromosomes – rodlike structures inside the nucleus of each
  cell in the body
   store and transmit genetic information
 Genes – segments of DNA located along the chromosomes
 DNA – substance of which genes and chromosomes are made.
DNA and Mitosis
 Mitosis – when DNA duplicates itself
 Each new cell receives an exact copy of the original chromosomes
 Allows one-celled fertilized ovum to develop into a complex
  human being composed of many cells
  Chromosomes, Cells, and Sex:

              The 22 pairs of chromosomes that are
              not sex chromosomes

              • 23rd pair of chromosomes
              • Determines sex
              • XX = female, XY = male

  Gametes     Sex cells: Sperm and ova

  Zygote      Sperm and ovum united
How New People Are Formed
 New people are created when two gametes (sex cells)
 Normal # of chromosomes in a cell = 46
 Gametes are formed through a cell division process called
   Meiosis – when the number of chromosomes in each cell is
 Gametes only have 23 chromosomes
   When they combine, the new zygote again has 46 chromosomes
 Fraternal/dizygotic
   2 ova are released and fertilized
   Genetically no more alike than regular siblings
 Identical/monozygotic
   Occurs when a zygote that has started to duplicate separates
    into two clusters of cells that develop into two individuals
   Have same genetic makeup
 Two forms of the same gene
   Remember, except for the XY pair in males, all chromosomes
    come in corresponding pairs
   Two forms of each gene occur at the same place on the
     One inherited from the mother and one from the father
   Each pair = Allele
 Homozygous – alleles from both parents are alike
   Child will display the inherited trait
 Heterozygous – alleles from each parent differ
   Relationships between the alleles determine the trait that will
  Dominant – Recessive Inheritance
 Occurs in many heterozygous pairings
 Only one allele affects the child’s characteristics
   Dominant allele – one that affects the child’s characteristics
   Recessive – one that has no effect on the child’s
 Example:
   allele for dark hair is dominant – D
   Allele for blonde hair is recessive – d
   DD = dark hair
   Dd = dark hair
   dd = blonde hair
X – Linked Inheritance
 When a harmful allele is carried on the X chromosome
 Males are more likely to be affected because their sex
  chromosomes do not match (XY)
 Females – any recessive allele on one X chromosome has a
  good chance of being suppressed by a dominant allele on the
  other X
 But the Y chromosome is only about 1/3 as long and lacks
  many corresponding genes to override those on the X
 Example: hemophilia
Incomplete Dominance & Polygenic
 Incomplete Dominance
   A pattern of inheritance in which both alleles are expressed
   Results in a combined trait intermediate between the two
   Example:
     Sickle cell trait – heterozygous
     One dominant and one recessive = carrier
     Sickle cell anemia – child inherits two recessive genes
 Polygenic Inheritance
   Many genes influence a characteristic
   Complex, still don’t know a lot about it
Genomic Imprinting and Mutation
 Genomic imprinting
   Alleles are imprinted, or chemically marked, so that one pair
    member (either the mother’s or the father’s) is activated,
    regardless of its makeup
   Often temporary
 Mutation
   A sudden change in a segment of DNA
   Perminant
   Chromosomal Abnormalities
 Most defects result from mistakes during meiosis when the
  ovum and sperm are formed
   Chromosome pair does not separate properly
   Part of a chromosome breaks off
 Down Syndrome
   Problems with the 21st chromosome
     Failure to separate properly during meiosis, baby inherits 3 chromosomes
 Sex Chromosome Abnormalities
   Presence of an extra chromosome (either X or Y) or absence of
    one X in females
Environmental Contexts for
 Family
 Socioeconomic status and family functioning
 Affluence
 Poverty
 Neighborhoods, towns and cities
 Cultural context
Family Influences on Development
 Family – social system of interdependent relationships
 Direct
   2 – person relationships
      Example: parent-child, marital partners, siblings
 Indirect
   Third parties
      Interaction between any two family members is affected by others present in the
      Example: parents who have a warm, considerate marital relationship praise and
       stimulate their children more
 Adapting to change
   Changes from within and outside the family
      Example: birth of a new baby, change of occupation
Socioeconomic Status (SES)
 Social status
   Years of education
   Job prestige and skill required
 Economic status
   Income
SES and Family Functioning
 Timing and duration of family life cycle
   Lower SES – marry and have children earlier, have more
   Higher SES – marry and have children later, have less children
 Values and expectations
   Lower SES – tend to emphasize external characteristics
    (obedience, politeness, neatness, cleanliness)
   Higher SES – emphasize psychological traits (curiosity,
    happiness, self-direction, cognitive and social maturity)
 Education, status of women
   Education of women fosters patterns of thinking that greatly
    improve quality of life for both parents and children
SES and Family Functioning (cont.)
 Communication and discipline styles
   Lower SES – greater use of coercive discipline and physical
   Higher SES – tend to use discussion techniques and teach
    children how to make independent decisions
 Children’s cognitive development
   Lower SES – less likely to provide stimulation for children
   Higher SES – more likely to provide simulation
   Risks of Affluence
 Affluent parents – highly prestigious jobs and six-figure
 Children:
   More likely to use alcohol and other drugs
   Report high levels of anxiety and depression
   Report less emotional closeness and supervision from parents
 Unavailable parents
   Overscheduled (never around)
   Demanding (make excessive demands for achievement)
Importance of Regularly Eating Dinner
as a Family
    Poverty: Who Is Poor?
 15.1% in the United States as of 2012
   Parents under age 25 with young children (50 %)
   Elderly living alone, especially women (50%)
   Ethnic minorities
   Women
   Children under 18 (22%)
     Hispanic children 35 %
     Native-American children 32 %*** (not updated)
     African-American children 38 %

Poverty: Homelessness
 On any given night, approximately 350,000 people in the U.S.
  have no place to live
 23 % of homeless are families with children
   Majority with children under age 5
   Poor school attendance
      Approximately 25 to 30% who are old enough do not attend school
   Health issues
   Developmental delays
 Homelessness mostly due to:
   Decline in availability of government-supported, low-cost housing
   Release of mentally ill people from institutions who receive no help
    to adjust to ordinary life
Benefits of Strong Community Ties for
Children and Adults
 Social interaction, activities – reduce family stress and
  enhance adjustment
   Frequent contact with friends, relatives, regular religious
    service attendance
 Cooperation to provide clean, safe environment
 Participation in important tasks
 Mutual assistance
 Neighborhood resources have a greater impact on low SES
  young people
   Impact can be either positive or negative
 In-school and after-school programs
   Provide enrichment activities – associated with improved
    academic performance and reduction in emotional and behavior
 Neighborhood organizations and informal social activities
   Predict increased self-confidence, school achievement, and
    educational aspirations
Towns and Cities
 Rural areas and small towns
   Youths more likely to be given important tasks (caring for
    livestock, operating a snowplow, playing in the town band)
     Usually alongside adults – instill strong sense of responsibility and teach
      practical and social skills
   Stronger connections between settings (ex. Schools serve as
    community centers, more frequent parent-teacher interaction)
   Active involvement in the community is likely to be greater
    throughout the life span
   Public places are relatively safe and secure
Extended Families
 Three or more generations live together
 More common in minority cultures
 Benefits
   Reduces stress of poverty
     More employed adults in the household
   Assistance for all generations
     Grandparents play large roll in guiding younger generations
     Adults who face employment, marital, or child-rearing difficulties receive
      assistance and emotional support
     Caregiving is enhanced for children and the elderly
   Generally enhanced emotional bonds and support
Individualistic and Collectivistic
                       People define themselves
                           separate group
                        as part of a entities;
                       separate from other people
                        Stress importance of group
                       goals over individual goals
                        Largely concerned with
                       individual/personal needs
                        Value interdependent self
                       and goals
                        More common in Asian
                       Value independent self
                       More common in western
                        societies like the U.S.
Public Policies and Lifespan
 Public policies – laws and government programs designed
  to improve current conditions
 Example: if homelessness increases
   Build more low-cost housing, raise minimum wage, increase
    welfare benefits
 Example: Obamacare
 How Does the U.S. Compare to Other Nations
 on Indicators of Children’s Health and Well-
Well-Being Indicator   U.S. Rank    Canadian
Childhood Poverty         25           16

Infant Death              26           16

Teen Pregnancy            28           21

Education Spending        12           6

Health Spending           16           4
Policies for the Elderly
 U.S. was behind the curve in policies to protect the elderly
   Social Security – awarded in the U.S. in 1930s
      Decade behind most Western nations
 1960s – federal spending on programs for the elderly expanded
   Medicare, national health insurance program
 Only 4% of federal budget for the elderly goes to programs other
  than Social Security and Medicare (which are working so well…)
 Most Area Agencies on Aging operate at regional and local levels
   Communal and home-delivered meals, self-care education, elder
    abuse prevention, etc
   Poorly funded – help far too few people in need
How Much Does Heredity Contribute to
 Heritability estimates
   Measures extent to which individual differences in traits are due
    to genetic factors
   Ranges from 0 to 1.00
   Obtained from kinship studies
      Compares the characteristics of family members
      What percent of the time do family members/twins show a trait
      Ranges from 0 to 100%
 Example: heritability value for intelligence in children = .50
   Suggests that differences in genetic makeup explain about half
    of the variation in intelligence
Heredity and the Environment
 Range of reaction
   Each person’s unique, genetically determined response to the
   Can apply to any characteristic
   2 important points
     Shows that because each person has a unique genetic makeup,
       we respond differently to the same environment
     Sometimes different genetic – environmental combinations
       can make two people seem similar (when in reality they are
 Ben’s intelligence increases steadily with the quality of the
 Linda’s rises sharply, then falls off
 Ron’s begins to increase only after the environment becomes
  modestly stimulating
Genetic – Environmental Correlation
 Our genes influence the environments we are exposed to
 Changes with age
   Passive correlation
      Younger ages
      Child has no control over its genetic influence on environment because parents
       provide environments influenced by their own heredity
   Evocative correlation
      Children evoke responses from the environment that are influenced by their own
      Responses strengthen child’s original style
        Ex. Active friendly baby is likely to get more social stimulation than a passive quiet
   Active correlation
      Children extend their experiences beyond immediate family
      Niche-Picking – Actively seek environments that fit with their genetic tendencies
        Ex. Well-coordinated muscular child spends more time at after-school sports &
          musically talented child joins school band and plays violin
 The Epigenetic Framework
 Views relationship between heredity and environment as bi
   Genes affect people’s behavior and experiences but their
    experiences and behavior also affect gene expression
 Epigenesis – development results from ongoing,
  bidirectional exchanges between heredity and all levels of
  the environment
 Example: providing a baby with a healthy diet increases brain growth
 Leads to new connections between nerve cells, which transform gene
 Opens the door to new gene-environment exchanges like advanced exploration
  of objects
 Further enhances brain growth and gene expression

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