my first post here. I've attempted to google this first but couldn't get anywhere with that and am hoping someone will be kind enough to help me so that I don't have to read a dozen papers to maybe find the answer. Thanks in advance.
in hg19 there are many instances of several thousand Ns. I'm not asking about those. There also happen to be several instances of a single N sitting in the middle of several thousand A|C|G|T s. For those instances, does "N" mean "highly variable" (as in each letter has a 25% chance of being there depending on the specific individual)? Or is it literally the case that there is one single "unknown" nucleotide sitting in a sea of thousands of "known" nucleotides. As a lay person this later case makes no sense to me. If it _is_ the case, could someone please explain?
Also, most larger regions of Ns seem to have 2-3 significant digits. But there is one chromosome where the N regions are indicated with 7-8 significant digits. Is this even possible? Science has no idea what the actual nucleotides are, but knows that there are _exactly_ 7,263,972 of them?
If there are good papers that deal with either of these issues I'd be happy to read those instead of having you type in a long explanation... I just can't find any existing discussion of these two issues.
Thank you!!!!!
in hg19 there are many instances of several thousand Ns. I'm not asking about those. There also happen to be several instances of a single N sitting in the middle of several thousand A|C|G|T s. For those instances, does "N" mean "highly variable" (as in each letter has a 25% chance of being there depending on the specific individual)? Or is it literally the case that there is one single "unknown" nucleotide sitting in a sea of thousands of "known" nucleotides. As a lay person this later case makes no sense to me. If it _is_ the case, could someone please explain?
Also, most larger regions of Ns seem to have 2-3 significant digits. But there is one chromosome where the N regions are indicated with 7-8 significant digits. Is this even possible? Science has no idea what the actual nucleotides are, but knows that there are _exactly_ 7,263,972 of them?
If there are good papers that deal with either of these issues I'd be happy to read those instead of having you type in a long explanation... I just can't find any existing discussion of these two issues.
Thank you!!!!!
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