CHAPTER 2 – BIOLOGICAL &
ENVIRONMENTAL FOUNDATIONS
S.L.O’S
Discuss how genes are transmitted from one
generation to the next
Consider reproductive choices
Describe environmental contexts for development
Understand the relationship between heredity
and environment
WARM-UP
1. Take a minute and think of several children
you know.
2. Write physical and behavioral features similar
with their parents.
3. Think about this…
1. Did any child show a combination of both parents?
2. Did any child resemble just one parent?
3. Did any child not resemble any parent?
Why do you think this is? Let’s discuss…
THE BIOLOGY OF IT ALL…
Phenotypes – directly observable characteristics
Phenotypes depend on the following 2 things:
Genotype – blend of genetic information
(heredity/nature)
Lifelong experiences (nurture)
GENETIC FOUNDATIONS
We are made up of cells with
chromosomes (rodlike structures
with stored genetic information)
We have 23 pairs of
chromosomes
Chromosomes have
deoxyribonucleic acid or DNA
DNA
Genes clone themselves through the process of
mitosis
Mitosis allows identical genetic formation so
nothing changes
This is done when genes send instructions for
making rich assortment of proteins to the
cytoplasm, area surrounding the cell (Berk, 2008)
MITOSIS & MEIOSIS
SEX CELLS
Gametes
sex cells (sperm & ovum)
Each gamete contains 23 chromosomes
Formed through cell division process, meiosis
When gametes combine, a pair of chromosomes meet
and form a new person or a zygote
MEIOSIS
1. Chromosomes pair up and each make a copy of
itself
2. Crossing over – each chromosomes joins with
another gamete forming a new hereditary
combination
3. Chromosomes split up forming 23 singles
4. When fertilization happens, a zygote is formed
with 46 chromosomes or 23 pairs
Down syndrome occurs when there is an additional
chromosome in the mix
MITOSIS & MEIOSIS
IS IT A BOY OR GIRL?
22 of the chromosome pairs are matching
(autosomes)
It is the 23rd pair that determines the sex
Females have a pair that is called XX
Males have a pair that is called XY
MULTIPLE BIRTHS
Dizygotic – fraternal twins
Fertilization of 2 ova; 2 sets of chromosomes
Monozygotic – identical twins
Fertilization of 1 ova which developed in 2 clusters
PATTERNS OF GENETIC INHERITANCE
Dominant-recessive inheritance
Incomplete dominance
X-linked inheritance
Genetic imprinting
Mutation
Polygenic inheritance
Allele – 2 forms of the same gene occur at the same
place in a chromosome
Homozygous -chromosomes from both parents are similar
Heterozygous –chromosomes from parents are different
Dominant inheritance – strong & in your face
Recessive inheritance – hidden & can skip a
generation but considered carriers or the trait
Modifier genes – enhance or dilute the effects of other
genes
INCOMPLETE DOMINANCE
Pattern of inheritance in which both alleles are
expressed in the individual’s physical and behavioral
characteristics determined by genes and environment
Sickle cell trait/sickle cell anemia – round blood cells
become sickle shaped which clog the blood vessels and low
oxygen level causing intense pain, swelling and tissue
damage
Occur with African Americans – low-risk of malaria
GENETIC IMPRINTING
Genes are chemically activated from either
parent
Help understand genetic patterns
Ie: asthma – tend to have mothers who have it
Diabetes – tend to have fathers who have it
MUTATION
Germline mutation - in the cells
Somatic mutation – in normal cells that mutate
CHROMOSOMAL ABNORMALITIES
Down syndrome/trisomy 21
When the 21 chromosome does not separate during meiosis causing the child to have an extra chromosome
Consequences MR
Memory/speech problems
Limited vocabulary
Slow motor development
Short, flat faced, almond eyes
Breathing difficulties
Infants – heart & intestinal defects, hearing loss
GENETIC ABNORMALITIES
Sex chromosomal disorders
Disorder Description Treatment
XYY syndrome Extra Y; tall, large teeth, acne,
intelligence, male sexual development,
fertility normal
None
needed
Triple X
syndrome (XXX)
Extra X; height & impaired verbal
intelligence. Female sexual
development & fertility is normal
SPED for
verbal
ability
Kinefelter
syndrome (XXY)
Extra X; height & body fat distributed
like a female, incomplete sex
characteristics, sterile, impaired verbal
intelligence
Hormone
therapy;
SPED for
verbal
Turner
syndrome (XO)
Missing X; short, webbed neck,
incomplete sec characteristics, sterile
and impaired spatial intelligence
Hormone
therapy;
SPED for
spatial
REPRODUCTIVE CHOICES
Genetic counseling
Prenatal diagnosis & fetal medicine
Adoption
ACTIVITY
1. Think back to your childhood
2. Think of people who made a difference in your
development
3. Let’s list them down as a group and compare
4. Let’s discuss
ENVIRONMENTAL CONTEXTS FOR
DEVELOPMENT
Family – lifelong models
Direct influences – interaction between child &
another
Indirect influences – what a child witnesses
Adapting to change –adapting to change in one
family member to another
How does a parent interact with a newborn?
How does that same parent interact with a toddler?
SES & FAMILY FUNCTIONING
SES
Years of education
Prestige and social status
Income
Timing of parenthood & family size
Discuss this… What is the difference in problem-
solving skills between low and high SES? Why is
this so?
AFFLUENCE AND SES
SES
Poverty •Strive to become better or remain the
same?
Low •Character education
•Strive to become better
Middle •Family connections
•Parental/family support
•Stimulated
High
6 figure incomes
•Talked to at a young age
•Allowed to discover
•Stimulate infants
NEIGHBORHOODS/SCHOOLS
Should offer additional resources and social ties
High SES – volunteer work; additional support,
education, fun
Low SES – active participants; physically fit, stay
away from or participate in violence, abuse found
LET’S TALK ABOUT IT
Who is responsible for raising a child?
CULTURAL CONTEXT
Extended family households
Many adult relatives
Common in minority groups
Protects development from stressful conditions
Collectivist societies
Groups needs and goals
Individualistic societies
Individual needs and goals
Public policies
Addresses social problems
RELATIONSHIP BETWEEN HEREDITY &
ENVIRONMENT
Development is a mix between heredity and environment.
Heredity influences children’s responses to environmental stimuli
Boys with aggressive genes tend to be more aggressive
Environment influences can stimulate or cause regression in heredity
Children with negative relationships with parents become anti-social
Boys with aggressive genes who are abused become extremely aggressive
Children may be genetically inclined to behavior a certain way but they may also actively choose environments that complement their heredity (nich-picking)