Fig 1. The pair-pull-part strategy shared by mitosis and meiosis.Mitosis and Meiosis II (left and right upper panels) bypass genetic information entirely, instead using the proximity of newly replicated sister chromatids to direct cohesin proteins to tie them together. Meiosis I (center upper panel) identifies homologous chromosomes, not with sequence-recognition proteins, but by their ability to form inter-chromosome base pairs, and uses changes in their physical connectivity (crossovers) to stabilize the pairing. For all 3 divisions, correct orientation for separation is directed by the physical tension on their connection to spindle fibers (middle panels), and the actual separation occurs when the cohesin loops are cut by checkpoint-regulated separase proteins (lower panels). Blue and green lines, chromosomes and chromatids; black lines, DNA; yellow circles, centromeres; orange rings, kinetochores; orange arrows, spindle fibers; white loops, cohesins; scissors, separases.
Well-designed animations can help students to focus on the underlying principles and processes in biology rather than relying on rote memorization. We present question-driven, terminology-free, “candymation” videos for teaching the concepts behind mitosis and meiosis as an example.