Chapter 4: Genes, Evolution, and Behaviour
- Genetic Influences:
- Chromosomes and Genes:
o Genotype: the specific genetic makeup of an individual and it never changes.
o Phenotype: the observable characteristics produced by that genetic endowment, it does change.
o Chromosome: a tightly coiled molecule of DNA that is partially covered by protein. All cells in the human
body have 46 chromosomes, except sex cells, which have 23.
o Genes: inside the DNA, hereditary blueprints that contain the information about the individual’s
characteristics, potentials, and limitations. Code for the production of protein.
Dominant genes: the characteristic it controls will be displayed.
Recessive genes: the characteristic it controls will not be displayed, unless the partner gene
received from the other parent is recessive as well.
Polygenic transmission: when a number of gene pairs combine their influences to create a single
Gene Therapy: Brian Druker – discovered Gleevec, which targets and turns off proteins that
cause CML. This type of research is looking very important for the future.
o Zygote: formed from an egg cell and sperm cell.
o Alleles: alternate forms of a gene that produce different characteristics.
- Genetic Engineering – The Edge of Creation:
o Recombinant DNA procedures: using certain enzymes to cut the long threadlike molecules of genetic
DNA into pieces, then combine them with DNA from another organism, and insert them into a host
organism, typically a bacterium. The new DNA combination continues to divide and produce many
copies of itself. This has been used to produce human growth hormone.
o Gene knockout: to alter a specific gene in a way that prevents it from carrying out its normal function.
- Behaviour Genetics Techniques:
o Heredity: the passage of characteristics from parents to offspring through genes.
o Heritability: how much of the variation in a characteristic within a population can be attributed to
o Heritability Coefficient: an estimated statistic that determines the extent to which variation in a
particular trait can be attributed to genetic differences in a population.
o Concordance: the probability that a pair of individuals will both have a certain characteristic, given that
one of the pair has the characteristic. If the concordance is high in people who are closely related to one
another, then this points to a genetic contribution, particularly if they have lived in different
environments. There are a few research methods based on this principle:
Adoption Study: studying a person who was adopted early in life and comparing their
characteristics with the biological parents, and with the adoptive parents.
Twin Studies: studying the characteristics of sets of monozygotic and dizygotic twins.
Monozygotic twins: identical twins, they are developed from the same fertilized egg,
therefore they are genetically identical.
Dizygotic twins: fraternal twins, they are developed from separate fertilized eggs;
therefore they share 50% of their genetic endowment.
- Genetic Influences of Behaviour:
- Heredity, Environment and Intelligence:
o Characteristics such as intelligence are affected by environ