Class 2 Sept 13 Developmental
Psychology: Genetic Basis of Child
• Mechanisms of Heredity
1. Biology of Heredity
I. Each parent contributes 23 chromosomes.
II. The first 22 are autosomes, and the 23 are the sex chromosomes
III. DNA is the main component of the chromosomes.
IV. Rosalind Franklin: Took X-rays of atoms in order to understand their
structure. She already hinted in 1950 that DNA was a double helix.
V. DNA is made up of a phosphate, sugar, and nitrogenous base. These bases
are adenine, guanine, thymine, and cytosine. A combines with T, and C with
VI. Human genome project
VII. Genotype and phenotype: how one becomes the other (behavioral and
2. Single Gene Inheritance
I. Allele: The same gene on a pair of chromosomes.
II. Remember Mendel’s pea experiment.
III. HOMOZYGOUS alleles are the same, while HETEROZYGOUS alleles are
IV. Heterozygous alleles will have a dominant and a recessive gene.
3. Genetic Disorders
I. Sickle cell and cystic fibrosis are both recessive genetic disorders.
II. Remember the working of the punnet square and the probability of a gene
being expressed in different situations.
III. The gene for Cystic Fibrosis is on chromosome 7. IV. Twin studies are ideal for studying this.
V. Too many/few chromosomes can a