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Lecture 3

CHILD AND YOUTH lecture 3 :)


Department
Child and Youth Studies
Course Code
CHYS 1F90
Professor
Lauren Mc Namara
Lecture
3

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CHYS 1F90 – Lecture 3
CHYS 1F90 – Lecture 3
Dr. J. McNamara
Dr. J. McNamara
Fall/Winter 2011
Fall/Winter 2011
Bronfenbrenner’s Ecological Systems Theory
Bronfenbrenner’s Ecological Systems Theory
Ecological Systems Theory
Ecological Systems Theory
Detailed characterization of various environmental influences on development
Environment is a series of nested systems
Microsystem
Mesosystem
Exosystem
Macrosystem
Ecological Systems Theory
Ecological Systems Theory
Contributions
Contributions
•richest description of environmental influences
•suggests interventions for optimizing development at various levels of society
Criticisms
Criticisms
generalizability from one environment to next questioned
not complete; a complement to existing theories
Lecture Overview - Biological Models of Development
Lecture Overview - Biological Models of Development
Principles of hereditary transmission
How are genes expressed?
Chromosomal and genetic abnormalities
Behavioural genetics
Determining heritability
Interaction of heredity and environment: Nature and Nurture
Conception
Conception
Father’s sperm + Mother’s ovum = Zygote with 46 chromosomes in total
23 from each parent
Mitosis
Mitosis
Mitosis begins after fertilization
–The process by which a cell separates chromosomes in its nucleus into two identical cells
The Chromosomes
The Chromosomes
Each chromosome contains genes
Sections of chromosomes
Made up of DNA
The chemical code for development
Why Not 50% mom – 50% dad?
Why Not 50% mom – 50% dad?
Meiosis & Crossing-Over
Meiosis & Crossing-Over
•Chromosomes within sperm cells divide in half before they fertilize an ovum or egg cell
•Chromosomes with egg cells divide in half before they are fertilized
•The “splitting” is random
•The randomness creates variation in the resulting embryo
•This complicated process is call “Meiosis”
Male or Female?
Male or Female?
23rd pair of chromosomes
Males have X and Y
Females have X and X
Sex of child determined by father’s sperm
Male or Female?
Male or Female?
Note 23rd chromosome:
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What Do Genes Do?
What Do Genes Do?
Direct production of amino acids necessary for forming new cells
Guide cells to develop different parts of body
Regulate pace and timing of development
May “turn on” or “turn off” other genes
Impacted by environmental factors
Gene Expression
Gene Expression
Alleles influence many characteristics
One pair of genes
One member from mother, one from father
Simple dominant – recessive inheritance
some alleles are stronger than others
Dominant alleles
Recessive alleles
Gene Expression
Gene Expression
If an allele is homozygous…
Both gene are dominant or both recessive
–To express a trait one must have a homozygous recessive allele
If an allele is heterozygous…
One gene is dominant and one is recessive
Dominant Genes
Dominant Genes
–Dominant genes are almost always stronger than recessive genes
Chromosomal Abnormalities
Chromosomal Abnormalities
How do chromosomal abnormalities occur?
Inherited congenital defects
Mutation (spontaneous or triggered by prenatal environment)
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