Sex chromosomes
XX in women, XY in men.
Not all pairs match
Most human chromosomes come in matching pairs, one from the mother and one from the father. One pair is different.
In which people is that special pair a perfect pair?
What this lesson covers
The idea
Humans have 22 chromosome pairs with a maternal and a paternal copy plus one pair of sex chromosomes: women have a perfect pair, XX, while men have a mismatched pair, XY, with a short Y.
Not all pairs match
Most human chromosomes come in matching pairs, one from the mother and one from the father. One pair is different.
In which people is that special pair a perfect pair?
- Women
- Men
- Both men and women
Find the sex pair
Press Next step.
XX and XY
We have 22 ordinary pairs. The last pair is the sex chromosomes. In women it is a perfect pair of two X's. In men it is an X and a short Y.
Human beings have 22 pairs of chromosomes with a maternal and a paternal copy, plus one pair of sex chromosomes. Women have a perfect pair, XX, while men have a mismatched pair, XY, with a short Y.
Notes
22 pairs of ordinary chromosomes plus one pair of sex chromosomes: women XX, a perfect pair; men XY, a mismatched pair with a short Y.
Check yourself
How many pairs of human chromosomes are not the sex chromosomes?
Answer: 22
Most human chromosomes have a maternal and a paternal copy, and there are 22 such pairs. One more pair is the sex chromosomes.
Which sex chromosomes do women have?
What is the mismatched pair of sex chromosomes in men?
Why are the sex chromosomes called odd among human chromosomes?
- One X and one short Y. That mismatched pair is found in men.
- Two short Y chromosomes. Y is the short chromosome found in men, paired with an X. Women have a perfect pair, both called X.
- Two X chromosomes, a perfect pair — correct. Yes!
- A normal-sized X and a short Y — correct. Yes!
- Two normal-sized X chromosomes. Two X chromosomes are a perfect pair, found in women.
- Two short Y chromosomes. Men have one X and one short Y, not two Y chromosomes.
- They have no maternal or paternal copy. Women have a perfect pair of X chromosomes. Men have an X and a short Y.
- They are not always a perfect pair — correct. Yes!
- There are 22 of them. There are 22 ordinary pairs, and one pair of sex chromosomes.