"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!)
Splitting a banana: seedless fruits are all clones
Calico cats: random inactivation of an X chromosome
Meiosis, crossing over, and the SRY gene: XX males and XY females (HHMI)
Cell Cycle Checkpoints: 4 strikes allowed
Evolution of Y chromosome over 300 million years: are the X and Y really homologous? (HHMI)
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
• 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
• Why Sex Is Not Binary New York Times 10/25/18

Additional material

• How many times have your cells divided?
• Meiosis and sexual cycle review; nondisjunction (QuickTime movie from ebook)