An own goal from Gregor Buchanan and Michael Tidser’s disputed penalty lifted the Greenock side six points clear of fifth-placed Raith though they had a few anxious moments after Andy Stirling narrowed the deficit for a Sons side who refused to throw in the towel.
Home boss Jim Duffy said: “It was a tough match but every game in this division is tough – no team puts the tools away.
“It was frantic at times. For us, as stretched as we are and the injuries that we have, I thought it was a fantastic result.”
Morton began the match with real purpose, creating several good openings in the early exchanges. The best of them saw a Ross Forbes shot deflected narrowly wide following smart play from Aidan Nesbitt.
But the home side were not to be denied and they made the breakthrough when Nesbitt picked up a loose ball at the edge of the box and burst forward before firing low across goal where Buchanan had the misfortune to turn into his own net.
The Cappielow men could have been two up on the half-hour when an excellent effort from Forbes hit the cross-bar.
Sons almost grabbed an equaliser when an improvised over-head kick from Sam Stanton was headed off the line by Mark Russell.
Stanton then picked out Robert Thomson whose header from close range was just wide.
Nesbitt continued to look dangerous for Ton on the restart as he found space down the wing to cross for Forbes but his shot was well pushed away by substitute keeper Mark Brown who had earlier replaced the injured Alan Martin.
Morton were gifted a golden opportunity by referee John Beaton when he awarded them a hotly contested spot-kick after Darren Barr was adjudged to have clipped Nesbitt’s heels.
And, after protests from the Sons defence, Tidser stepped up to slam home the penalty and double his side’s lead.
The two-goal advantage only lasted four minutes as Dumbarton hit back when Stirling was given space on the edge of the box and his shot was deflected into the corner of the net leaving keeper Derek Gaston helpless.
The visitors nearly snatched a point at the death when substitute Christian Nade fired over from a promising position but Morton held firm to take the points.
Duffy had special praise for man-of-the-match Nesbitt, adding: “I thought Nizzy was outstanding. He was a real threat throughout the game and typified the attitude of all the players today.
“I thought the commitment was there for everybody to see. Over the balance of play I think we deserved to win.”
Dumbarton boss Stevie Aitken, who confronted referee Beaton at the end of the game, declared: “If the penalty was for me of course I would take it, but Darren Barr has not got a clue about it.
“The Morton player actually kicks Darren so it’s harsh, but sometimes you get them and sometimes you don’t.
“At 2-0 it was difficult but credit to the payers – they got the goal and we had a chance and could’ve got a draw out of it but I think the damage was done in the first 25 minutes.
“I said to the ref I thought the penalty call was a poor decision, and Darren wasn’t watching the player so how could he commit a foul? So it’s disappointing but we’ve had a great run and a good December and the players deserve credit for that.
“We just need to dust ourselves down and go again.”