Biology / Unit 4 Bio 0843 short lesson, about 20 seconds
Sister Chromatids and the Centromere
Captions available
The idea
After DNA replication, a chromosome consists of two identical sister chromatids joined by cohesin proteins at a constricted region called the centromere.
In practice
A replicated chromosome's two sister chromatids remain joined at the centromere until a later division stage pulls them apart.
Where people slip
Sister chromatids are identical copies of one chromosome, not separate chromosomes — they count separately only after splitting apart.
Your place on the trail
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