First of all, cut the black and red licorice sticks into one inch strips. Now make two equal lengths of licorice strands by putting the pieces of licorice onto the string, and do this by alternating the red and black pieces. Now gather together four different colours of gummy bears, as well as the the marshmallows, and the toothpicks you gathered earlier.
Take two colours of gummy bears and pair them together. You can also pair red and orange gummy pairs together and green and yellow ones together.
Now take a gummy bear and thread it onto the toothpick. And thread the marshmallow onto the toothpick carefully as well so that it is in the center of the toothpick and next to the gummy bear. Now thread the gummy bear on the toothpick in a way that it is next to the marshmallow.
In order to progress even further in your experiment, repeat the step five to make more gummy bear-marshmallow toothpicks. You should make as many toothpicks as you can.
Now what you have to do is to take one strand of licorice and start attaching the gummy bear-marshmallow toothpicks to it. You have to be very careful while doing that and do it in a way that you connect one of these toothpicks at each of the red pieces. After you are done with the first strand, go ahead and take the second stand and connect it to other free side of the toothpick. After you are done with that, once again you have to connect the toothpicks to the red pieces of licorice.
Now, yoou should have a "ladder" with the red and black licorice stands that will be representing and making the sides of the ladder, while on the other hand, the gummy bear-marshmallow toothpicks must be making the rungs of the ladder.
Now at the end, hold your candy ladder up and turn the top of it anticlockwise in order to add twists to the ladder. You have your DNA model ready.