chapter 3: genetic bases of child development 3.1 mechanisms of heredity 3.2 genetic disorders 3.3...
TRANSCRIPT
Chapter 3: Genetic Bases of Child Development3.1 Mechanisms of Heredity
3.2 Genetic Disorders
3.3 Heredity Is Not Destiny
3.1 Mechanisms of Heredity
The Biology of Heredity
Single Gene Inheritance
Behavioral Genetics
The Biology of Heredity
The first 22 pairs of chromosomes are autosomes and the 23rd pair are sex chromosomesGenotype is one’s complete set of genes and phenotype is one’s physical, behavioral, and psychological features
3.1 Mechanisms of Heredity
Single Gene Inheritance
Pairs of alleles can be either homozygous or heterozygous Dominant allele: its chemical instructions are followedRecessive allele: its chemical instructions are ignoredIncomplete dominance: one allele doesn’t dominate the other completely
3.1 Mechanisms of Heredity
Sickle Cell Trait: An Example of Incomplete Dominance
Behavioral GeneticsMany behavioral genotypes reflect polygenic inheritance, which involves many genes.Behavioral geneticists rely upon twin studies and adoption studies.Intelligence, psychological disorders,and personality are all affected by heredity.
3.1 Mechanisms of Heredity
An Example of Polygenic Inheritance
3.2 Genetic Disorders
Inherited Disorders
Abnormal Disorders
Inherited Disorders
Many disorders are triggered when a child inherits two recessive alleles.
Examples include cystic fibrosis, PKU, and Tay-sachs disease
Most inherited disorders are very rare.
3.2 Genetic Disorders
Abnormal Chromosomes
Some people are born with too many, too few, or damaged chromosomesPeople with Down Syndrome usually have an extra 21st chromosomeA number of disorders are caused by missing or extra sex chromosomes
3.2 Genetic Disorders
3.3 Heredity Is Not Destiny
Paths from Genes to Behavior
Reaction Range
Changing Relations between Nature and Nurture
The Nature of Nurture
Paths from Genes to Behavior
Genes never cause behavior directly
The behavioral consequences of genetic instructions depends on environment
3.3 Heredity Is Not Destiny
Reaction Range
A genotype can lead to a range of phenotypes depending on the environment People with PKU genotype: those who eat normal diet will be mentally retarded, but those who eat special diet will have normal intelligence
3.3 Heredity Is Not Destiny
Reaction Range of Intelligence
Changing Relations between Nature and Nurture
Passive G-E relation: parents pass on genotype and environmentEvocative G-E relation: different genotypes evoke different responses from the environmentActive G-E relation: actively seek environments related to their genes
3.3 Heredity Is Not Destiny
The Nature of Nurture
Parents don’t provide exactly the same environments for all of their children (non-shared environmental influences)
Parents provide the child’s genes and environment, but the child also influences her own environment
3.3 Heredity Is Not Destiny
The Relation Between Genes and Environment