Assignment on human karyotypes

[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.

 

[Blueshift5]

I would like to provide some insights and clarifications on your questions regarding human karyotypes.

1) The placement of the X and Y chromosomes at the end of row 3 and 4, respectively, on karyotype charts is a convention that has been established for convenience and consistency. This placement does not have any biological significance and does not imply that the X and Y chromosomes are not considered as a 23rd pair. In fact, the X and Y chromosomes are always considered as a pair, as they determine the sex of an individual. The reason for their placement at the end of rows 3 and 4 is simply because they are the smallest chromosomes and it makes it easier to fit all the chromosomes on the chart.

2) It is possible for two individuals to have the same karyotype and different phenotype. This is because the phenotype is determined not only by the genetic makeup (karyotype) but also by environmental factors and gene expression. For example, two individuals with the same karyotype may have different physical features due to differences in their diet, lifestyle, or exposure to certain environmental factors. On the other hand, two individuals with the same karyotype may also have a similar phenotype if they have inherited certain traits from their parents. However, in the case of genetic abnormalities such as Klinefelter's Syndrome, it is highly unlikely for two individuals to have the exact same features caused by the syndrome. This is because genetic abnormalities are caused by specific changes in the DNA sequence, which are unique to each individual. Therefore, while two individuals may have the same karyotype and similar physical features, it is highly unlikely for them to have the exact same features caused by a genetic abnormality.

I hope this helps to clarify your questions and provides a better understanding of human karyotypes. If you have any further questions, please do not hesitate to ask. Good luck with your assignment!