A smart Vucinic strike just past the hour and a superb Marchisio goal in the 74th minute saw the reigning champions beat a Bologna side who had won three in a row including victories over Champions League-chasing Fiorentina and Inter Milan.
The win takes Antonio Conte's side on to 65 points and puts more pressure on second-placed Napoli to beat visiting Atalanta on Sunday (1400 GMT) as they try to keep the title race alive.
Bologna have slipped to 12th on 35 points.
Catania moved within two points of the European places by beating Udinese 3-1 thanks to Alejandro Gomez's second-half double and a Francesco Lodi strike.
Rolando Maran's side are now seventh on 45 points behind Inter and Lazio who both have 47 points and play on Sunday at Sampdoria and Torino respectively.