c
In a mistake in meiosis, the fertilized egg has two copies of chromosome 21.
Down's Syndrome is also called Trisomy 21 because affected people have three copies of chromosome 21. How is this possible?
a
Either the sperm cell or the egg cell has two copies of chromosome 21.
b
Either the sperm cell or the egg cell has one copy of chromosome 21.
c
In a mistake in meiosis, the fertilized egg has two copies of chromosome 21.
d
In a mistake in mitosis, the fertilized egg has two copies of chromosome 21.
1 answer