Detailed notes for AP Bio unit 5 - Unit 5 covers heredity, which is how traits are passed down from one generation to the next - The main topics in this unit are: - Meiosis: a type of cell division that produces haploid gametes (sperm and egg cells) from diploid cells - Genetic diversity: the variation in genes and alleles within and among populations - Mendelian genetics: the principles of inheritance based on Gregor Mendel's experiments with pea plants - Non-Mendelian genetics: the patterns of inheritance that deviate from Mendel's laws, such as incomplete dominance, codominance, multiple alleles, polygenic traits, and epistasis - Environmental effects on phenotype: how external factors can influence the expression of genes and traits - Chromosomal inheritance: how chromosomes and genes are inherited and how chromosomal abnormalities can affect phenotypes - Some key concepts and terms to know for this unit are: - Homologous chromosomes: pairs of chromosomes that have the same size, shape, and genes - Crossing over: the exchange of genetic material between homologous chromosomes during prophase I of meiosis - Independent assortment: the random distribution of homologous chromosomes during metaphase I of meiosis - Nondisjunction: the failure of homologous chromosomes or sister chromatids to separate properly during meiosis - Genotype: the genetic makeup of an organism - Phenotype: the physical appearance or observable characteristics of an organism - Allele: a variant form of a gene - Dominant allele: an allele that masks or overrides the expression of another allele in a heterozygote - Recessive allele: an allele that is masked or hidden by another allele in a heterozygote - Homozygous: having two identical alleles for a gene - Heterozygous: having two different alleles for a gene - Monohybrid cross: a cross between two individuals that differ in one trait controlled by one gene with two alleles (e.g., AA x aa) - Dihybrid cross: a cross between two individuals that differ in two traits controlled by two genes with two alleles each (e.g., AaBb x AaBb) - Punnett square: a diagram that shows all possible outcomes and probabilities of a genetic cross