biological approach Flashcards
assumptions of the biological approach:
1) all human behaviour has a
biological origin (genes, the nervous system, and neurochemistry)
2) behaviour and human genes have evolved so we’re more likely to survive
3) the best method to study people is the scientific method
genes
segments of DNA molecules that code physical features
neurochemistry
much of our behaviour relies on transmission of chemicals in the brain –
neurotransmitters
genotype
your actual genetic make-up
phenotype
the physical expression of a genotype that can be influenced by the environment
evolution
the change in the characteristics of biological populations over successive generations
neurotransmitter
chemical messengers that transmit nerve impulses across the synaptic gap
what do _____ study?
behaviour geneticists - whether behavioural characteristics are inherited the same way as physical characteristics
what are twin studies used to determine and how?
the likelihood that certain traits have a genetic basis by comparing concordance rates between pairs of twins
define concordance rates
the extent to which both twins in a pair share the same characteristic
how can monozygotic twins and dizygotic twins be used to discover genetic basis?
-if identical twins are found to have higher concordance rates than non-identical twins this would suggest a genetic basis
-this is because MZ twins share 100% of each other’s genes, whilst DZ twins share about 50%
how are monozygotic twins born?
a fertilised cell splits into two and forms two separate embryos
how are dizygotic twins born?
two separate egg cells both become fertilised by different sperm cells at the same time
what should the concordance rates between MZ twins be if a particular characteristic is a genetic one?
100%, lower for dizygotic twins
family studies
involve finding out if relatives of those with a trait are more likely to have the trait than the general population
adoption studies
involve comparing a trait/characteristic between adopted children and their biological or adoptive parents
______ + ______ = phenotype
genotype + environment
(to a large extent, an individual’s phenotype is determined by its genotype)
how do monozygotic twins show the interaction between inheritance and environment?
-they have the same genetic makeup and they look alike, but they possess
different phenotypes
-any differences you may see between them (personality, tastes, aptitudes) are due to differences in their experience or environment
rita and holly are identical twins who were separated at birth.
when they finally met each other at the age of 35, they were surprised at how different their personalities were
rita is much more social and out-going than holly
use your knowledge of genotype and phenotype to explain this difference in their personalities
-holly and rita have identical genotypes as they are MZ twins
-they have a predisposition to develop the same personalities as each other unless another factor intervenes.
-for them to have developed different personalities it must be influenced by being in different environments
-presumably rita was encouraged to be sociable and lively and holly was not
-their phenotypes (personalities) are different because of this
phineas gage
an explosion sent an iron bar through his head, destroying a large portion of his frontal cortex:
-personality change
-lost his ability to inhibit antisocial behavior
-was angry when he used to be relaxed
what causes atypical behaviour?
(+ examples)
imbalances in the number of neurotransmitters
(lack of serotonin → depression)
hormones
-chemicals that affect behaviour
-they are released into the bloodstream where they travel to the target cells which are activated by them specifically
what happens when a nerve impulse reaches the end of one neuron?
-a neurotransmitter is released
-it travels from one neuron to the next across a synapse
excitatory neurotransmitters
trigger action potentials in the receiving neuron and stimulate the brain into action
