Biology / Unit 5 Bio 0969 short lesson, about 20 seconds
The Tetrad
Captions available
The idea
A tetrad is a pair of homologous chromosomes, four chromatids total, held together by chiasmata after crossing over in prophase I.
In practice
Each of a cell's 23 homologous pairs forms one tetrad, so a human cell in prophase I holds 23 tetrads.
Where people slip
A tetrad's four chromatids are not four separate chromosomes — separation is still divisions away.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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