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)