I did a DNA extraction of a fruit where I basically blended it, add enzymes to destroy membrane and then after I did that we had to put it into hot water. What does this water do?

Hello CrazCo

Without the full experimental procedure, it can be really difficult to provide a reason. However, given that you mentioned that you added enzymes to the mixture, the water could serve the purpose of destroying the enzymes before they start interacting the the DNA and hence, destroying it.

The water would act as a solvent - allowing the enzymes to function and of course to dissolve the compounds that it has broken down.

I suppose you mean you put the sample in a hot bath, not that you added water in the container of the sample, but correct me if I am wrong.

 

Do you know the temperature of that "hot water"? If you don't know the exact temperature, could you touch the water without burning yourself?

Enzymes are designed to function at a certain temperature range. All else being equal, higher temperatures will make reactions go faster.

Too hot the water would destroy enzymes. So I think this is to mobilize and dissolve the cell contents into the solvent rather than for enzymatic actions.

Cell lysis can be achieved by cooking, though not really by enzymatic actions. The latter can be used to destabilize cell walls and similar structures but the membrane remains relatively intact. An additional step as e.g. chemical, mechanical lysis is subsequently required (or cooking for that matter).