BStill

Hello Charon, OK. I am starting to understand a little more. So, lets say were talking about the paternal and maternal chromosomes 15. Now lets say we sequence these choromosome. When there is a difference in single base pairs between these chromosomes this is considered a SNP? So for example. GGCCTTAACCTTGG CCGGAATTGGAACC GGCATTAATCTTGG CCGTAATTAGAACC At position 4 and 9 are the loctions of the SNP. Is this right?

Hello, I am having a difficult time understanding the concept of SNP's and polymorphisms in general. So far, I understand that a SNP is a change in a single nucleotide in the DNA sequence that occurs in greater than 1% of the population. If everyone's genome is not sequenced, then how does anyone know that this particular change in nucleotide is in fact in greater than 1% of the population? If we have a paternal and a maternal chromosome, does the SNP have to occur in one of these or both of these? So is there a chromosome set that everyone is comparing these changes in nucleotide to? Any help would be appreciated.