|In almost any discussion of yDNA research there are frequent references to STRs, SNPs, and other acronyms. <-- Click the linked words for FTDNA's definitions.)
A greate explanation of SNPs and STRs was given by Kerry Farmer and repeated by Warren Power to me in an email. Here's an Excerpt of Warren's email. In it he mentions the repeated letters "G", "T", "A", and "C." If you ever saw the movie "GATACA" you might have picked up on these letters which represent guanine (G), adenine (A), thymine (T), or cytosine (C).
These are the enzymes which make up the nucleotides referred to in SNPs (Single Nucleotide Polymorphisms).
Put a bunch of 'em in a row randomly and you might create a pattern like this: GACGACGACGACGAC. Such repeating patterns for STRs (Short Tandem Repeats). These STRs are the "Markers" or numbers we refer to when we compare STR results.
What's the relationship between the two? I've often wondered that myself. I just learned (as of today, 9/11/2014), that a SNP can actually appear INSIDE an STR. I had often wondered about that ever since I first comprehended what the two are.
I felt this concept was so important I created a page to describe it. Click here to learn about SNPs Inside STRs.
Short Tandem Repeat (STR)
A short DNA motif (pattern) repeated in tandem. ATGC repeated eleven times would give the marker a value or allele of 11.
Single Nucleotide Polymorphism (SNP)
A SNP, Single Nucleotide Polymorphism, is a change in your DNA code at a specific point.