Transcript Chapter 2

Chapter 2:
Genetic Bases of Child Development
Chapter 2: Genetic Bases of
Child Development
Chapter 2 has two modules:
Module 2.1 Mechanisms of Heredity
Module 2.2 Heredity, Environment, and
Development
Mechanisms of Heredity
The Biology of Heredity
Single Gene Inheritance
Genetic Disorders
Module 2.1 Mechanisms of
Heredity
• What are chromosomes and
genes?
• What are dominant and
recessive traits?
• How are they inherited?
• What disorders are inherited?
• Which are caused by too
many or too few
chromosomes?
Module 2.2 Heredity,
Environment, and
Development
The Biology of Heredity
A Quick Review
• Cell
• Sperm
• Egg
• Chromosome
• DNA
The Biology of Heredity
Chromosomes
• Autosomes
• Sex chromosomes
Gene
• Genotype
• Phenotype
Single Gene Inheritance
Genes come in different forms known as
alleles
• Homozygous or heterozygous
• Dominant or recessive allele
• Incomplete dominance
Think about these terms as you look at the
next slide.
Sickle Cell Trait: An Example of
Incomplete Dominance
Do you see why?
• Individuals with one
dominant and one recessive
allele have the SC trait.
Genetic Disorders: Inherited
•
Often triggered through inheritance of two
recessive alleles
•
Inherited disorders (Table 2.2)
Genetic Disorders:
Chromosomes
•
Too many, too few, or damaged
chromosomes
•
Abnormal chromosome numbers (Table 2.3)
Heredity, Environment, and
Development
Behavioral Genetics
Paths From Genes to Behavior
Module 2.2 Heredity,
Environment, and
Development
• What methods do
scientists use to study
the impact of heredity
and environment on
children’s
development?
Module 2.1
Mechanisms of
Heredity
• How do heredity and
environment work
together to influence
child development?
Behavioral Genetics
Behavioral genetics: inheritance of
behavioral and psychological traits
•
Polygenic inheritance
Let’s look at an example on the next slide.
An Example of Polygenic
Inheritance
•
Phenotypes
distribute with
extremes at
both ends
•
Combined
activities of
many separate
genes
Methods of Studying Behavioral
Genetics
Twin studies and adoption studies
•Compare identical and fraternal twins or
adoptive and biological siblings to measure
the influence of heredity
•If identical twins are more alike than fraternal
twins, this implicates heredity.
Behavioral Genetics
True or false?
Cognitive abilities, psychological disorders,
substance abuse, and personality are all
affected by heredity.
Behavioral Genetics
Plomin’s Adoption
Studies
Child intelligence
correlated more strongly
with biological mother’s
intelligence than
adoptive mother’s
intelligence
Hereditary and
environmental
contributions to
intelligence
proposed
And so…
Heredity and environment interact
dynamically throughout development.
Paths From Genes to Behavior
Behavioral consequences of genetic
instructions
• Depend on environment in which those
instructions develop
•
Reaction range
•
Heritability coefficient
Paths From Genes to Behavior
What are the paths?
Heredity and
environment
interact
dynamically
throughout
development
Genes can
influence the
kind of
environment to
which a child is
exposed
Environmental
influences
typically make
children within
the same
family different
Paths From Genes to Behavior
Epigenesis
• Continuous interplay between gene and
multiple levels of environment drives
development
•
Heritability coefficient
Paths From Genes to Behavior
Niche-picking
• Deliberately seeking environments that fit
one’s heredity
Take a minute to think about environments
you sought out as a child.
What was your niche?
2.2 Paths From Genes to
Behavior
Why aren’t all children in the same family
identical?
• Environmental influences
•
Non-shared environmental influences
•
Child influences
The Relation Between Genes
and Environment