Biology Question Help Pls! Will medal/fan!!

Question

nitroster · Answer

What is the correct karyotype notation of this patient based on the diagram above:

a. 45, XO abnormal female (missing an X chromosome)

b. 46, XX normal female 

c. 47, XX female, + 18 (extra copy of this chromosome)

d. 47, XY male, + 21 (extra copy of this chromosome)

misssmartiez · Answer

Chormozomes are in pairs, meaning two in each pair. Chromosome twenty-one is the smallest human chromosome.


Usually Down syndrome occurs when the host has an extra, or three chromosomes (trisomy), chromosome, instead of TWO. 
 
So it isn't A, it isn't missing any chromosome, it would be only one located if it was.

It isn't C because the extra chromosome ISN'T located in 18.

And it isn't normal because it has more than two chromosomes.

misssmartiez · Answer

So, it would be what? @Nitroster?

It would be D. Think about it :)

misssmartiez · Answer

If you still need help, google or look up extra chromosome in 21, and it will explain to you all about it, and what syndromes and malfunctions can form because of this mutation.

anonymous · Answer

that's correct! Also, you can look specifically at pairs of chromosomes to rule out answers. For example, if you look at the unnumbered pair (the ones that determine sex) you can see that the left one looks like an X, but its pair is not the same size, so it must be a Y. You can also can look at the numbered pairs to see if there are any extra. Hope this helps and don't forget to medal :)