Genes and behaviour

Question 1

Genes

Answer 1

1. Genes produce proteins, not behaviour
2. but genes can influence behaviour through effects on proteins on neurons, hormones, brain and muscles
3. resulting behaviour is affected by the environmental conditions in which it develops
4. genetic traits are flexible, expressed behaviour is gene x environment
5. genes influence the mechanisms for learning

Question 2

what are genes

Answer 2

a length of dna that encodes the information for constructing a particular protein

Question 3

how do they relate to observable traits

Answer 3

1. genotype - the entire set of genes an individual possesses (from parents)
2. phenotype - observable characterists, influenced by genes and environment

Question 4

alleles and genetic diversity

Answer 4

1. alleles are versions of a given gene
2. individuals have one or two alleles of a gene, but multiple alleles can exist in the population
3. dominant will be expressed if heterozygous

Question 5

to what extent is behaviour transmitted by genes

Answer 5

Challenges of behavioural genetics research:
1. difficulty in defining and quantifying behaviour
2. environmental influence on behaviour
3. within and between individual variation
4. involvement of many genes
5. different genes function in different tissues at different times during the development of an organism
6. Weber et al - captive reared mice placed in sand filled arena, F1 offspring hybrid built escape tunnels, backcrossed F1 with other species, 50% escape tunnels, evidence for a single, dominant locus that controls building of escape tunnels

Question 6

how do genes contribute to behaviour

Answer 6

1. gene expression acts at different phenotypic levels
2. expression of a gene can influence expression of other genes, activity of the other cell, other tissues and organs, developmental processes, activity of brain, muscles, messenger systems
3. environmental influences act on gene expression and/or on phenotype
4. total phenotypic variance in a trait is based on additive effects of genetic variance and environmental variance
5. trait heritability = proportion of phenotypic variance associated with genetic variance

Question 7

selective breeding for behaviour

Answer 7

artifical selection: rats selected for maze running activity

Question 8

genetic mutation

Answer 8

1. most mutations are harmful or neutral in their effects; only rare are mutations beneficial
2. they happen spontaneously very rarely or by the action of the exposure to radiation
3. knockout - lab strain in which an artificially induced mutation inactivated gene’s normal function

Question 9

twin studies

Answer 9

1. twin and adoption studies investigate and environmental influences on human behaviour and cognition
2. MZ - genetically identical, shared prenatal and postnatal environment
3. DZ - genetically different, shared environment prenatal and post natal
4. adopted children - genetically different, different prenatal environment, shared postnatal
5. how strong the correlation between twins is for a behaviour shows if there’s a genetic component
6. problems with this - heritability estimates are not comparable across environmental contexts, biased sampling across different family situations, comparisons don’t clearly separate genetic and environmental effects

Question 10

non genetic inheritance

Answer 10

1. factors in one individual influence the behaviour or development of an individual without passing on genes
2. vertical transmission - between generations, similar patterns to genetic inheritance, can skip generations
3. horizontal transmission - within generations
4. e.g. maternal effects like diet preference, social learning

Question 11

genetic vs non genetic transmission of behaviour

Answer 11

1. genetic - information carrier is DNA, action is alteration of protein production, direction of transmission is vertical only
2. non genetic - information carrier is actions, imitation and media, action is alteration of higher processes, direction is vertical horizontal or both

Question 12

epigenetics

Answer 12

1. environmentally sensitive modifications of dna and associated proteins that regulate gene expression without altering the genetic sequence itself
2. epigenetic modifications can be transient or stable and can be induced by environmental factors
3. no convincing evidence of epigenetic inheritance in humans though it has been evidenced in plants and simpler animal species