Genes

The specific set of genes carried by an individual organism

Genotype

Having two identical copies or a specific gene or alle

Homozygous

Having two different alleles or versions of a specific gene

Heterozygous

An Allele that expresses its trait in the phenotype even if only one copy is present

Dominant Allele

An allele whose trait is is expressed in the phenotype only when two identical copies are present

Recessive Allele

The dominant characterisic is expressed in the allele

Phenotypic result of carrying one dominant allele and one recessive allele

A specific variant or version of a gene.

Allele

Any chromosome that is NOT a sex chromosome

Autosomal Chromosome

X-linked FMR1 gene mutation; most common inherited cause of intellectual disability; males more severely affected

Fragile X Syndrome

The dynamic relationship between biological genetics and environmental influences

Nature Vs Nurture

Studying a known genetic modification first to determine its resulting observable characteristics

Gene-to-Behaviour Approach

Staring with a clustered behavioural trait and searching downward for the underlying genes

Behaviour - to- Gene approach

What causes Fragile X syndrome?

Too many repeats of a CGG sequence in the FMR1 gene. Over 200 repeats switches the gene off.

Groups of related behavioural characteristics that consitently run in famillies

Behaviour clusters

Austism Spectrum Disorder and ADHD

Example of behaviour to gene mapping

To Pinpoint specific genes responsible for recognised clusters of behaviour

Goal of Behaviour- to- Gene Research

The extent to which trait variation among individuals is explained by genetic differences

Heritability

Expressed as a proportion between 0 and 1.0 (or 0% to 100%)

Heritability Scale Range

Indicates no genetic influence on the variation of a trait

Heritability Coefficient of 0

Indicates genetics completely explains the variation of a trait

Heritability Co Efficient of 1.0

Approximately 0.80 (80%)

Heritability of height

80% of trait variation in a population is due to genes, 20% to environment

Meaning of 80% Heritability

Reared together: idendical - .55 fraternal .38

Reared apart:idendical - .55 fraternal .38

Twin Studies: Alienation - Reared Together vs Reared Apart correlations (Based on data from Tellegen et al., 1988)

Males express full effects more readily because they only have one X chromosome and a lack of a second X chromosome to compensate if a gene is turned off

Expression of X- linked genetic conditions in males

Females have a second X that usually contains an active, unaffected copy of the gene to produce the neccessary protein

Compensation mechanism in for X - linked traits

A condition caused by a specific gene being swiched on the X chromosome

Fragile X syndrome primary genetic mechanism

The overall level of protein produced or expressed by the gene

Determinant of trait display in gene inactivation

Genes interact by exacerbating, compensating for, or altering the expression of other mutated or switched-off genes

Gene-gene interaction during early development refers to

Triplication of Chromosome 21 (Tripsomy 21)

Genetic cause of downsyndrome

The ability of other functional genes or a normal allele to produce proteins that offset the loss or a mutated or inactivated gene

Genetic compensation

The ability of other functional genes or a normal allele to produce proteins that offset the loss of a mutated or inactive gene

Genetic compensation

Different environmental influences shaping gene expression across development

Key reason for phenotypic differences in monozygotic twins or similar genotypes

The presence of two X chromosomes requires mutations on both for full expression if the trait is recessive

Biological reason for lower x linked condition frequency in females

When the presence or state of one gene worsens the functional defect caused by another switched off gene

Exacerbation in gene interaction

A minimal level of functional protein required to prevent a clinical or phenotypic characteristic from appearing

Protein expression threshold concept

As a functional backup, producing neccessary proteins when the other X chromosome has an inactivated gene

Role of non mutated X chromosome in biological females

how early childhood experiences and environmental factors interact with genes to cause long lasting adult behavioural traits

Primary research in Michael Meaneys studies

Cross- fostering (switching biological pups between high- lick and low -lick mothers)

Experimental method to rule out pure genetic inheritance in rat pups

Effect of epigenetic chemical tags on the stress response gene in low nurture pups

The chemical tag supresses or turns off the gene required to regulate the stress response

High nurturance prevents/ removes chemical tags that turn off stress regulating genes, allowing normal protein expression

Role of early environmental nurturance in gene regulation

Nurture directly influences nature by modifying chemical tags on genes to alter behaviour long term

Summary of Michael Meaneys conclusion regarding nature and nurture

The developmental process of raising offspring

Animal Rearing refers to

What is a chemical tag in genetics

a small molecular group attached to DNA, RNA, or associated proteins that controls whether genes are turned on or off without changing the underlying DNA sequence

What is RNA in genetics (ribonucleic acid)

a vital molecule found in all living cells that helps turn the genetic instructions in DNA into the proteins your body needs to function