The Human Heritage: Genes and the Environment. The Development of Children (5 th ed.) Cole, Cole & Lightfoot Chapter 2. A World of Possibilities….
The Development of Children (5th ed.)
Cole, Cole & Lightfoot
“If we go to all the trouble it takes to mix our genes with those of somebody else, it is in order to make sure that our child will be different from ourselves and from all our other children.”
—François Jacob, The Possible and the Actual
Mitosis: A Process of Cell Replication
Meiosis: A Source of Genetic Variation
Sexual Determination: Another Source of Variation
Model of DNA
The process of somatic (body) cell duplicationanddivision that generates all the individual’s cells except sperm and ova
The twice-over process of germ cell (i.e., sperm and ova) division that results in a zygote (with 46 chromosomes) at conception
Variation enhanced by “crossing over” during first phase...
Human X and Y chromo-somes
The Laws of Genetic Inheritance
Genes, the Person, and the Environment
The Study of Genetic Influences on Human Behavior
Genotype + Environment Phenotype
Gregor Mendel (1822-1884): Garden peas
The effect of environment on the expression of a gene for fur color in the Himalayan rabbit.
Under normal conditions only the rabbit’s feet, tail, ears, and nose are black. If fur is removed from a patch on the rabbit’s back and an ice pack is placed there, creating a cold local environment, the new fur that grows in is black.
The process that makes some traits relatively invulnerable to environmental events