Like Y-DNA STRs, autosomal STRs are counts of repeated genetic code. As autosomal DNA recombines each generation, the number of markers shared with a specific ancestor is reduced by half each generation.
Heroin acts as a lipid soluble âprodrugâ within the brain, meaning that heroin itself is inactive but it is metabolized into an active form within the body. After crossing the blood-brain barrier, heroin is metabolized into morphine, which actively binds to opiate receptors in the brain producing the high.
Codeine is not itself centrally active, and must first be converted via first pass metabolism into morphine by the cytochrome P450 enzyme CYP2D6. Codeine is also metabolised into the inactive norcodeine via the CYP3A4 enzyme system.