Biology Of Behaviour Flashcards
Chromosome
Cellular structure that holds out genetic information in threadlike strands of DNA
DNA (deoxyribonucleic acid)
Genetic material that makes up chromosomes
Large coiled molecule that contains genes
Genes
Small segments of DNA that contain information for producing proteins
Genome
All genetic information contained in our DNA
Alleles
Different forms of genes
Dominant genes
Show their effect even if there is only one allele
Recessive genes
Show effects only when both alleles are the same (recessive form)
Genotype
Specific collection of genes that we carry as a part of our genetic makeup
Phenotype
Observable characteristics with relation to genetics
Behavioural genetics
3 principles of behavioural genetics that are relevant to psychology
- Relationship between specific genes and behaviour is complex; behaviours derive from dozens or hundreds of genes, not one or two
- by studying human twins and adoptees, or manipulating genes in animals, behavioural geneticists may disentangle the contributions of heredity and environment to behaviour
- Environment influences how and when genes affect behaviour
Monogenetic transmission
Hereditary passing on of traits determined by a single gene
Polygenic transmission
Many genes interacting to create a single characteristic
Heritability coefficient
Ranges from 0-1
1 being solely due to genetics
0 being solely due to environment
Fraternal twins
Develop from 2 different eggs fertilized by 2 different sperm
Aka dizygotic twins
Identical twins
Develop from a single fertilized egg that splits into two independent cells… aka monozygotic twins
Twin studies
- fraternal twins share half as many genes as identical twins (50% vs 100%)
- if a trait is genetically influenced, identical twins should be more similar in that trait than fraternal twins
- if genetics play no role, identical twins will be no more alike than fraternal twins in that specific trait
Adoption studies
- studying adopted individuals and comparing them to biological parents and adoptive parents
- if environment is more influential on a trait, the child will be more like adoptive parents
- if genetics are more influential on a trait the child will be more like the biological parents
Twin-adoption studies
-study twins, both identical and fraternal, who were raised apart and those who were raised together
Gene by environment studies
- assess how genetic differences interact with environment to produce a certain behaviour in some people but not in others.
- studies directly measure genetic variation in parts of the genome and examine how such variations interacts with different kinds of environments to produce different kinds of behaviours
- differs not in whether an individual has the gene, but how the gene presents itself
- some genes may vary in length of DNA sequence (genetic marker)
Genetic markers
- differences in length of DNA sequences for a particular gene
- researchers take a DNA sample then assess crucial environmental factors such as trauma, stress, in people with and without the genetic marker
- determine whether individuals raised in a particular environment are more or less likely to develop some trait (violence, high intelligence etc)
Gene manipulation in non-human animals
- genetically engineering of genes in experimental animals
- conditional manipulation of gene expression or permanent alteration of the genome
- involves inactivation or over expression of specific gene
Antisense injection
Form of genetic engineering where a gene (antisense) is injected to block the gene from being translated into protein
- if that gene plays a role in a particular behaviour, then inactivation should lead to observable changes
- eg. Brain-derived neurotrophic factor is a protein thought to support memory process, so inactivation will produce memory impairments
Viral mediated gene transfer
Genome alteration
- involve changing genetic material BEFORE conception (unlike genetic manipulation which is done to adult animals)
- genome alteration are present not only in adulthood, but also throughout prenatal and postnatal development
- knockout vs transgenic
Knockout (genome manipulation)
Inactivation of a gene
Transgenic (genome manipulation)
Introduction of a novel gene (usually human origin)
Epigenetics
- how the environment changes gene expression
- genes can be changed by an individuals behaviour, or behaviours can by modified by genetic expression
- food we eat, drugs we take, exposure to certain chemicals are a few things that can have epigenetic consequences