SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation.
On most plays, the center will snap the ball directly into the quarterback's hands. In a shotgun formation, the center snaps the ball to the quarterback lined up several yards behind him.
Most of the time, the snap of the ball is the first thing that moves on the offense. Use your peripheral vision to keep track of the ball. Also, focus on the shoulder pads of the o-line. Many o-lineman rock their shoulders before they fire out.