Mon Prof Augmenté
One X or two X
Red-green color blindness is inherited through chromosomes. Boys have one X and one Y, so a single changed X can cause it; girls have two X chromosomes, so they need two changed X chromosomes.
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Age 13: open this week
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In the picture
- The badge sits on the left adult’s notched long chromosome, a changed X.
- The badge sits on the right adult’s short chromosome, a Y.
- The badge sits on the boy’s notched long chromosome, his only X.
- The badge sits on the girl’s plain long chromosome, her second X.
Examples
- Telling red and green sweets apart can be hard.
- Matching red and green socks can be difficult.
Key takeaways
- Boys have one X and one Y; girls have two X chromosomes.
- A boy can be red-green color blind from one changed X, but a girl usually needs two changed X chromosomes.
Carry on in the app
Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
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