Why Are X and Y Chromosomes Placed Differently on Karyotype Charts?

[jen333]

Hi, I'm currently working on a bio assignment on human karyotypes and I've come across two questions that I've been researching on, but had no luck so far.
1) Why in some karyotype charts is the X chromosome(s) placed at the end of row 3 while the Y chromosome at the end of row 4?
my guess is that some may not consider X and Y chromosomes to be a 23rd pair since the only similarity between them is being a sex chromosome.

2) Could two individuals have the same karyotype and phenotype?
I was thinking that two individuals could have the same karyotype, yet different phenotype as that refers to physical features. However, when it comes to abnormalities such as Klinefelter's Syndrome, could two individuals have the same features that this syndrome causes??

help please! thanks a lot!

 

[Ouabache]

Hi, I'm currently working on a bio assignment on human karyotypes and I've come across two questions that I've been researching on, but had no luck so far.
1) Why in some karyotype charts is the X chromosome(s) placed at the end of row 3 while the Y chromosome at the end of row 4?
my guess is that some may not consider X and Y chromosomes to be a 23rd pair since the only similarity between them is being a sex chromosome.

I've looked at quite a few karyotype charts, typically X&Y chromosomes are grouped together, indicating they are the 23rd pair (http://www.ekcsk12.org/science/regbio/karyotype.gif
I haven't found any where the X & Y are in separate rows.

2) Could two individuals have the same karyotype and phenotype?
I was thinking that two individuals could have the same karyotype, yet different phenotype as that refers to physical features. However, when it comes to abnormalities such as Klinefelter's Syndrome, could two individuals have the same features that this syndrome causes??
help please! thanks a lot!

I think you are reading too much into this question. You know that phenotype refers to what the individuals look like. Identical-twins share the same karyotype (since they orginate from the same fertilized egg) and as the name identical implies, they have the same phenotype) .. Though as they age, environmental influences can cause a divergence in appearance.