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.
Up to four players can be behind the offensive line, but one is always designated the quarterback (defined as the player who receives the ball from the center). 1  Upon the snap of the ball, the quarterback becomes the ball carrier. The ball carrier has five options: 2  He may keep the ball and run with it.