Genes and Behaviour

Question 1

How do genes cause behaviour?

Answer 1

• genes produce proteins
• genes can influence behaviour through effects of those proteins (on neurons, hormones, brains, muscles)
• resulting behaviour is affected by environmental conditions in which it develops

Question 2

What are genes and gene expression?

Answer 2

• located on chromosomes located in the cell nucleus
• gene expression: transcription and translation
• transcription: new molecule produced from DNA, called RNA, mRNA (messenger) has copy of DNA transcribed into it, is then transported out of cytoplasm
• translation: mRNA translated into protein, ribosome reads the code of the mRNA and produces corresponding protein
• expression of gene influence: expression of other genes, activity of the cell/other tissues/organs, developmental processes, activity of brain/muscles/messenger systems

Question 3

What are genotypes and phenotypes?

Answer 3

• genotype: entire set of genes an individual possesses

- phenotype: the observable characteristics of an individual, influenced by genes and environment

Question 4

What are alleles and genetic diversity?

Answer 4

• people have 1/2 alleles (variants) of a gene but multiple alleles can exist in the population
• humans are diploids (2 copies of each chromosome)
• quantitative traits often show polygenic inheritance

Question 5

What are the challenges of behavioural genetics research?

Sokolowski, 2001

Answer 5

• difficulty in defining and quantifying behaviour
• environmental influences on behaviour
• within and between individual variation in behaviour
• involvement of many genes
• different genes function in different tissues at different development times

Question 6

What are traits determined by?

Answer 6

• genes and the environment in conjunction

- environment influences each step of pathway of gene expression (determines which genes produce proteins)

Question 7

What is trait heritability?

Answer 7

• proportion of phenotypic variance associated with genetic variance
• heritable does not mean genetically determined
• heritability of a trait is strongly dependent on the environment

Question 8

What is genetic mutation?

Answer 8

• effect of a mutation is critically dependent on where it occurs in germ-line or rest of the body
• most are harmful/neutral in effects
• mutagens and radiation increase mutation rate above spontaneous level

Question 9

What are twin studies?

Answer 9

• identical twins (monozygotic): genetically identical, same early and late environment
• non-identical twins: genetically different, same early and late environment
• adopted children: genetically different, different early (pre-natal) environment, same late environment
• problems with the approach: heritability estimates are not comparable across environmental contexts, biased sampling across different family situations (confounding factors), comparisons don’t clearly separate genetic and environmental effects