Evolution of the Y Chromosome

How did the human Y chromosome become so small relative to its X counterpart? This animation depicts the 300-million-year odyssey of the sex chromosomes that began when the proto X and Y were an identical pair.

5 minutes 38 seconds
Large: Play: MOV / WMV  |  Download: MOV (11 MB)/ WMV (21 MB)
Small: Play: MOV / WMV  |  Download: MOV (6 MB)/ WMV (5 MB)
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Meiosis

Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex?

5 minutes 52 seconds
Large: Play: MOV / WMV  |  Download: MOV (15 MB)/ WMV (23 MB)
Small: Play: MOV / WMV  |  Download: MOV (7 MB)/ WMV (6 MB)
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MIX-1

This animation shows how MIX-1 facilitates both chromosome condensation and dosage compensation.

3 minutes 38 seconds
Large: Play: MOV / WMV  |  Download: MOV (17 MB)/ WMV (26 MB)
Small: Play: MOV / WMV  |  Download: MOV (8 MB)/ WMV (7 MB)
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The Y Chromosome

The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution.

2 min 45 seconds (no audio narration)
View: MOV   |   Download: MOV  |   Learn More