I don’t know anything about chromosomes and google is further complicating it for me. I’ve always looked quite different from my peers and I wondered if there was something mixed in with me that would cause that, it turns out I have Scandinavian. In the chromosome breakdown part of the results it says that the Scandinavian is in chromosomes 12 and 21. Can anyone explain to me what this MEANS. Would that affect my physical appearance? Like my facial features? If not, what does it mean?
In: 14
We have chromosomes which are packages of dna.
When they were first seen it was recognised that we have 23 pairs of these (at least most of us do, there are some conditions that are due to having a specific extra chromosome (eg Down syndrome) or missing a chromosome (eg Turner’s syndrome)). It was then noticed that they are different lengths and this is seen in all people. So to differentiate them, rather than giving them names to tell them apart, it was easiest to number them. The longest pair were tagged as chromosome 1s. The shortest matching pair as chromosomes 22.
They also have similar band patterns when looked at by a microscope which helps differentiate the ones that are similar lengths.
There were then a pair left over. In females these ones looked the same. In males, one was shorter than the other. So rather than a number they got called X and Y. Chromosomes look like Xs so it makes sense to call it. The Y chromosome is much shorter, and when you look closely, on one side of the point there they join is very short. So it got called Y.
Here’s a picture of a set of human chromosomes. It includes an extra set of chromosomes so you can see both XX and XY examples
https://www.genome.gov/genetics-glossary/Karyotype
So for your case, the 12th chromosome is the 12th longest pair
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