"In the first step of meiosis, you don't divide by two, you multiply by two." - David C. Page

Supplementary videos

DNA packaging: histones and nucleosomes (HHMI)
Evolution of human chromosome #2: why do humans have 46 chromosomes, other great apes have 48?
Seedless Watermelon (Bite-Sci-zed triploid Colchicine tricks!)
Calico cat and X inactivation: random deactivation of an X chromosome
Meiosis, crossing over, and the SRY gene: XX males and XY females (HHMI)
Everything You Never Knew About Sex 10:50 "Why do men have nipples?"
Link Between Down Syndrome and Alzheimer's Disease: chromosome 21 has 250 genes

Extra credit readings

• Seedless Watermelon University of Arkansas 8/29/03
• Who Put The Navel In Navel Oranges? NPR 4/18/09
• First baby born with DNA from 3 parents CBS News 9/27/16
• Why do men have nipples? 6/18/79
• Brain cell regeneration sniffed out in adult humans New Scientist 2/15/07
• Ghost heart has a tiny beat Nature News 1/13/08
• People With Down Syndrome Are Pioneers In Alzheimer's Research NPR 8/25/14

Additional material

• Meiosis and sexual cycle review; nondisjunction (QuickTime movie from ebook)