Khan Academy
Khan Academy: Allele Frequency
Allele frequencies in populations and how they differ from genotype frequencies. [7:26]
Khan Academy
Khan Academy: Reproduction and Cell Division: Chromosomal Crossover in Meiosis I
Learn how homologous chromosomes exchange fragments in prophase I, tetrads, chiasmata, and alleles. [12:15]
Khan Academy
Khan Academy: Boveri Sutton Chromosome Theory
Overview of how chromosomes were first proposed as the carriers of Mendel's 'heritable factors' (what we now call 'genes'). [10:58]