A smart Vucinic strike 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.
"There are still some important games to play but tonight we sent out a signal and it was a match that was worth more than just the three points," said Juventus captain Gianluigi Buffon.
"Every time you win a game means there are fewer games left, and therefore the points mean more."
Bologna started brightly and could have taken an early lead when Alberto Gilardino was sent through by Alessandro Diamante's fine pass.
The striker, with 11 goals this season, tried to skip round the onrushing Buffon and, although the keeper timed his tackle perfectly, the ball dropped to Diamante whose long-range shot was heading for goal until it hit Giorgio Chiellini's back.
However, Juve slowly took control of the game, and were unlucky not to be leading at the break.
Sebastian Giovinco had their best chance after 18 minutes when he broke free from two defenders in the area only to scuff a weak shot straight at keeper Gianluca Curci.
A minute later Arturo Vidal skied his left-footed shot after being set up brilliantly by Vucinic.
Gilardino thought he had given Bologna an undeserved lead six minutes into the second half when he headed home Diamante's free-kick only to see the linesman's flag raised.
Juve midfielder Giovinco's fine approach play two minutes later saw him work a good shooting position and Curci did well to top his shot over the bar.
Vucinic made up for his side's mainly wayward shooting in the 62nd minute, receiving Marchisio's pass on the edge of the area and brilliantly spinning Edinaldo Naldo before squeezing his finish between Curci's legs.
Vucinic returned the favour 12 minutes later when Marchisio played a superb one-two with the Montenegrin on the edge of the area before slotting home with the outside of his right boot.
Earlier, 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.
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