Why do offspring resemble their parents?

• 7.1 Family resemblance: your mother and father each contribute to your genetic makeup.
• 7.2 Some traits are controlled by a single gene
• 7.3 Mendel learned about heredity by conducting experiments.
• 7.4 Segregation: you’ve got two copies of each gene but put only one copy in each sperm or egg.
• 7.5 Observing an individual’s phenotype is not sufficient for determining its genotype.

Probability and chance play central roles in genetics.

• 7.6 Chance is important in genetics.
• 7.7 A test-cross enables us to figure out which alleles an individual carries.
• 7.8 We use pedigrees to decipher and predict the inheritance patterns of genes.

How are genotypes translated into phenotypes?

• 7.9 Incomplete dominance and codominance: the effects of both alleles in a genotype can show up in the phenotype.
• 7.10 What’s your blood type? Some genes have more than two alleles.
• 7.11 Multigene traits: how are continuously varying traits such as height influenced by genes?
• 7.12 Sometimes one gene influences multiple traits.
• 7.13 Why are more men than women color-blind? Sex-linked traits differ in their patterns of expression in males and females.
• 7.14 This is how we do it: What is the cause of male-pattern baldness?
• 7.15 Environmental effects: identical twins are not identical.

Some genes are linked together.

• 7.16 Most traits are passed on as independent features: Mendel’s law of independent assortment.
• 7.17 Red hair and freckles: genes on the same chromosome are sometimes inherited together.