what is a trisomy 21?

Question

anonymous · Answer

trisomy 21 is actually more commonly known as down syndrome

anonymous · Answer

how many double chromosomes are there?

anonymous · Answer

does that answer your question?

anonymous · Answer

umm lemme see

anonymous · Answer

i do not know that but i don know that there is an extra 21'st chromsome hence the name trisomy 21

anonymous · Answer

oh okay. thanks. normal humans have 46 double chromosomes right?

anonymous · Answer

yes

anonymous · Answer

thanks so much!

anonymous · Answer

no problem

anonymous · Answer

Please note that it's "Down's syndrome" because it was described first by a physician named JL Down.

anonymous · Answer

Ok, so basically trisomy 21 is another name for Down's syndrome. As you've already said, human's normally have 46 chromosomes, or twenty-three pairs, which they are often divided into, because each pair looks similar. I'll include a picture. Anyways, normally each pair has 2, but in the event that there is a mutation, then there can be a monomy or a trisomy. A monomy is where there is only one of the two chromosomes in the pair, or a trisomy is an extra chromosome. So that's about it, hope the background info helps. :D

anonymous · Answer

do you know how many double chromosomes there are? i know there are 23 homologous pairs

anonymous · Answer

Here's a  good pic to show you...