PSYC1001 Lecture Notes - Lecture 4: Twin Study, Monoamine Oxidase A, Heritability
12 Jun 2018
School
Department
Course
Professor
Principles of Genetic Transmission
Researchers and Heredity of Psychological Traits
Typical and Atypical Development of Nature-Nurture Interaction
PRINCIPLES OF GENETIC TRANSMISSION
What are Genes?
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Chromosomes: threadlike structure found in the nucleus
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DNA: double-stranded molecule that makes up the chromosomes
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Genes: contain instructions for making particular proteins
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Basic units of heredity
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Each chromosome, or long double-stranded molecule of DNA
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A gene is expressed if it has been turned on to make its specific protein
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Genes and the Human Form:
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Zygote = sperm (23 chromosomes) + egg (23 chromosomes)
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Individual = started as a single cell = the zygote
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Each parent contribute to half of genetic makeup of their children
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Same gene, different forms = ALLELES
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2 alleles in the same form for a specific gene = homozygous
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2 alleles in different forms for a specific gene = heterozygous
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2 alleles for every gene = 1 from each parent
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RESEARCHERS AND HEREDITARY OF PSYCHOLOGICAL TRAITS
Genes and environment:
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Genotype = genetic blueprint; DNA passed from parent to child
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Phenotype = physical or psychological qualities
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Researchers try to understand how genetic and environmental factors combine to produce individual differences in
behaviour (phenotypes)
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Degree to which variation in a particular trait (e.g. IQ, shyness, schizophrenia) among individuals is due to
genetic differences among those individuals
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E.g. KINSHIP studies family studies, twin studies and adoption studies
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Use what we know about degree of relatedness to work out the relative contribution of genes and
environment to a particular phenotype
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Varies form 0 (no heritability) to 1 (completely heritable)
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Researchers estimate HERITABILITY:
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Behaviour genetics
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Degree of relatedness: probability of sharing genes among relatives
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Share 100% vs 50% of genetic makeup
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But often raised in the same environment at the same time
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Compare similarity of trait X in people differ in their degree of relatedness
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Monozygotic vs dizygotic twins
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Twin studies:
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Physical characteristics (e.g. height 80%)
Based on many studies, heritability estimates have been obtained for many human traits:
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2B - Developmental Psychology
Wednesday, March 7, 2018
8:59 PM
PSYCH 1001 Page 1
Document Summary
Dna: double-stranded molecule that makes up the chromosomes. Each chromosome, or long double-stranded molecule of dna. A gene is expressed if it has been turned on to make its specific protein. Individual = started as a single cell = the zygote. Each parent contribute to half of genetic makeup of their children. 2 alleles for every gene = 1 from each parent. 2 alleles in the same form for a specific gene = homozygous. 2 alleles in different forms for a specific gene = heterozygous. Zygote = sperm (23 chromosomes) + egg (23 chromosomes) Genotype = genetic blueprint; dna passed from parent to child. Researchers try to understand how genetic and environmental factors combine to produce individual differences in behaviour (phenotypes) Degree to which variation in a particular trait (e. g. iq, shyness, schizophrenia) among individuals is due to genetic differences among those individuals. Varies form 0 (no heritability) to 1 (completely heritable)
