P{RS5}7.18.1a and P{RS5}7.18.1b are in inverted orientation with respect to each other on the chromosome. The acentric fragment derived from Dp(2;2)bw^D-FRT by Scer\FLP1 mediated recombination usually moves towards the poles at anaphase. Those occasional fragments that do not move towards the poles are almost always straight (rather than folded as a hairpin) amd typically oriented with their ends towards the poles. This suggests that the heterochromatin insertion present at the tip of 2R in the Dp(2;2)bw^D-FRT chromosome can function as a centromere.