- DNA Sequence variation - A single nucleotide differs between individuals at the single base 1. This is a _____ _______ ______ 2. This is classified as a ____ ______ .

1. Single Nucleotide Polymorphism (SNP) 2. Allelic Variation (Allellic difference)

* Week 4 - Behaviour Genetics Flashcards by Luc King

What does it mean for something to be (x) % heritable?

(x) of variation in a behaviour in a population can be predicted by
variability between genes

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The first law of
behaviour genetics

All human behavioural traits are
heritable

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Examples of heritability

Texting on a cellphone is 52% heritable
Supporting property taxes is 41% heritable
Lifetime income – 50% heritable

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Comparison of the similarity of ____ and _____ twin pairs on particular traits can be used to estimate genetic influence

Monozygotic (MZ) & Dizygotic (DZ)

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Heritability is completely dependent on the ________

environment
(review plant pic on slide)

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How genetic variation
between people
correlates with
variation in a
behaviour in a
population

Heritability

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Which one of these definitions is Heritability
1. A measure of how
much of a trait was
inherited from parents
– Information of how a
gene influences a trait
– Influence of the
environment

How genetic variation
between people
correlates with
variation in a
behaviour in a
population

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Showing the effects of heritable genes through colours of pea plants

Mendelian
Genetics

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Who practically was the inventor / made enourmous discoveries to hertiability and genes.

Gregor Mendel

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Structures found in living cells that carry
genetic information

Chromosomes

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Each chromosome is a
single molecule of

DNA

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We inherit ___ chromosomes, and 1 comes from each _____

a) 2

b) Parent

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Each _____ molecule consists
of a long sequence of four chemical subunits called bases.

DNA (deoxyribonucleic acid)

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The four subunit bases of DNA are

adenine (A), cytosine (C), guanine (G), and thymine (T)
- attach (A-T), (G- C)

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A small segment of DNA that codes for the
production of a particular protein

Gene

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DNA Sequence variation
A single nucleotide differs between
individuals at the single base
1. This is a _____ _______ ______

This is classified as a ____ ______

Single Nucleotide Polymorphism (SNP)
Allelic Variation (Allellic difference)

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Individuals receive two versions of each gene, known as
______ , from each parent.

Allelles

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identical pair of
alleles on the two chromosomes
(e.g., GG).

Homozygous

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unmatched pair
of alleles on the two
chromosomes (e.g., GT).

Heterozygous

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An _______ trait occurs in
a phenotype where there is
incomplete dominance in the
heterozygous condition.

Intermediate

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An allele of a gene is said to be ______ when it effectively overrules the other allele

dominant

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An allele of a gene is said to be ______ when it effectively overruled by the other allele.

recessive

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The set of observable characteristics of an individual

Phenotype

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3 components of a Phenotype

Physical
Neural
Behavioural

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Many genes affect one phenotype

Polygenetic Inheritance

one gene can influence multiple phenotypes

Pleiotropy

There is significant genetic variation for most _______

phenotypes

International research program (1990-2003) to map and understand all human genes

Human Genome Project

Gene-Environment are not seperate and _______

Interplay

Genes do not _______, ______ or _____ behaviour. Rather, they ________ the probability that behavioural differences will be expressed in a given environment.

determine, control, cause. INFLUENCE

the genetic constitution of an individual organism that contributes to the phenotype

Genotype

Things about gene / environment.

- Genes correlate with the environment - Gene x Environment interactions are pervasive.

What is is known as when the Environment affects gene expression

Epigenetics

3 Gene Environment Correlations

Passive Active Evocative prevalence of type changes across development

- An individuals genes will correlate with their early environment - More prominent early in development

Passive GE-Correlation

- An individual’s genes influences the way that others respond to them - Present throughout development

Evocative GE-Correlation

- An individual’s genes influences their selective attention to different aspects of the environment - More prominent later in developmen

Active GE-Correlation

When two different genotypes respond to an environmental variation in a different way

GxE (Gene x Environment)

Candidate Gene Approach:

Foraging and Mothering (see week 4 slide if confused)

True / False. Early adversity makes some genes hard to read.

True

Epigenetics makes genes __________

unpredictable / hard to read

- How we fight disease. - How we cope with stress - How our brain develops and works all involve

genes

Examples of Epigenetic Inheritance

1. The Dutch Famine (1944 – 1945) and risk for obesity in offspring (including grandchildren!) 2. Holocaust Survivors and risk for PTSD and other mood disorders in offspring 3. Effect of parental trauma on offspring (Transgenerational transmission of trauma)

How genetic variation correlates with variation in a behaviour in a population

Heritability

The brains ability to changes in structure and function in response to life events.

Neuroplasticity

Brain growth involves 5 kinds of changes

-1.Neurogenesis (Proliferation) –2. Migration –3. Synaptogenesis – 4.Myelination – 5.Synaptic Pruning

- Process by which new neurons are formed in the brain. ■ Proliferation of neurons through cell division (mitosis) ■ Begins around the third or fourth week of prenatal life ■ 250 000 new neuron cells are created every minute during 5-25 weeks of age ■ By week 18, children have almost as many neurons as adults

Neurogenesis

■ Movement of new neurons to locations within the brain where they will serve their ultimate functions – E.g., nerve cells, skin cells, muscle cells etc. ■ Occurs in a variety of directions throughout the brain – Chemicals known as immunoglobulins and chemokines guide neuron migration.

Migration & Differentiation

Formation of insulating myelin sheath around the axon that allows signals to travel down axon more quickly

Myelination

■ Process where synapses are pruned or eliminated to increase efficiency of neural communication ■ Neurogensis and synaptogenesis à ”hyperconnetivity” = more synapses that can be used that are needed ■ Synaptic pruning fixes this and allows the brain to form normally ■ 40% of superfluous connections are pruned by: – Apoptosis: the death of neurons

Synaptic Pruning

■ Process where neurons form synapses with each other ■ Single neuron can form multiple synapses

Synaptogenesis

5 Periods of brain development

1. Prenatal 2. First two years 3. Two years to adolescence 4. Young and middle adulthood 5. Late adulthood

brains capacity to be shaped by experiences

Brain plasticity

True / False: Axons and dendrites dont continue to modify their structure and connections throughout the lifetime

False (THEY DO)

True / False: Dendrites continually grow new spines

True

■ Brain adapts in response to sensory information

Experience-Expectant Plasticity

Brain regions (mainly left hemisphere) become specialized for language – Infants: regions are ”expecting” input of speech – Speech input in channeled to expecting regions

Language Example Experience-Expected Plasticity

Regions associated with visual processing in blind children can be come specialized for hearing processing for children who are deaf)

Atypical Development Experience-Expected Plasticity

Infants with lesions don’t show same impairments as adults

Lesions/Trauma Experience-Expected Plasticity

Changes in brain wiring occur in response to an individual’s unique personal experiences and life circumstances

Experience-Dependent Plasticity

Times when specific experiences result in permanent changes in a child’s brain that cannot be altered

Critical Periods

Times in development when the brain is most susceptible to experiences, but changes are still reversible

Sensitive Periods

Why do we have critical/sensitive periods?

1. Brain may follow genetically fixed timetables associated with plasticity 2. Learning may produce brain changes that reduce plasticity 3. Experiences become increasingly stable over time

Individual differences in children in responses to experience

Resilience

“Resilient” children who are able to cope with stress and flourish despite environmental challenges

Dandelion Children

Children characterized by “low resilience,” who appear to wilt when faced with environmental challenge

Orchid Children