Biology / Unit 5 Bio 0967 short lesson, about 20 seconds
Crossing Over and the Chiasma
Captions available
The idea
Crossing over exchanges segments between nonsister chromatids of paired homologs, visible afterward as an X-shaped structure called a chiasma.
In practice
A recombination nodule marks the point where two nonsister chromatids break and rejoin, swapping DNA segments.
Where people slip
Crossing over swaps segments between homologs — it does not change gene order along a chromosome.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology