This puzzle shows a small four-segment bit of protein with blue band in the middle. The blue band is a cut. Cuts allow parts of the protein to be moved around separately. You can make cuts, but you must close them again for your score to count.
A blue cut means the cut ends are too far apart, so the cut can't be closed. A yellow cut can be closed by clicking on it.
To close the cut, wiggle until the cut turns yellow, then click on the cut. This should solve the puzzle.
Cuts are important in Foldit, so you might want to reset the puzzle and try again. Wiggling can't close all cuts. You can also click on one of the cut pieces, and use the move tool to move the pieces closer until the cut turns yellow. See the "Movin' On" puzzle for how to use the move tool. You may need to rotate the puzzle by dragging on the background to get the pieces to line up.
You can also try making your own cuts. Right-click (or control-click) on a segment, then select "Cut" from the wheel menu to insert a cut. Try inserting a cut between each segment, then wiggle and shake. Close the cuts again. This technique should get a high score.
Technical stuff: the backbone of the protein is held together by strong peptide bonds, a type of covalent bond. Normally, nothing you do in Foldit can break a peptide bond. Cuts let you break the backbone temporarily. The ends of the cut have to be close enough (and aligned the right way) for a peptide bond to form before you can close the cut.