Are enzymes able to heat up molecules so that they can react?
No enzymes do not heat up molecules so they can react.
Enzymes actually lower the energy needed for a chemical reaction to occur. Enzymes because of their chemical specificity provide a matrix where chemical reactions can occur. The matrix allows the chemical reaction to occur at a much lower energy level.
There are many reactions that would not occur at all without the functioning of enzymes. There are enzymes that catalyze the formation of DNA molecules. The combining of the bases with the sugar does not happen spontaneously without the presence of the specific enzymes. You can read about enzymes involved in DNA replication here.
Enzymes lower the energy that a reaction can occur, instead of increasing the energy available for the reaction to occur.