Playing with LEGO® made of DNA (... and now let's play)

We can identify a section of a DNA sequence (a 'word') with a letter, such as "A" or "a". We consider "A" complementary to "a" , "B" complementary to "b", and so on (capital letter complementary to lowercase letter). A DNA molecule can have a sequence consisting of a single sectiond or multiple sections in a row (for example "AcB" meaning that it is made of different sections). DNA molecules bind to each other in an 'antiparallel' way, as if the head of a sequence is bound to the foot of its complementary sequence, and vice versa (the arrowheads of the strands are on opposite sides of the helix).

Antiparallelism must be taken into account to design complementary sequences (and build your first LEGO® brick). For example, "AB" will bind (is complementary) to "ba" and not to "ab" or "AB".

Now go ahead designing your first brick: you have to choose 2 complementary sequences, selecting from the options with the selectors. Then check if your answer is correct when the molecules meet in the simulation. Your goal is to obtain this structure:

that can be schematized as of below:

(press the green flag to restart the simulations or the STOP sign to stop it. Reload the web page to reset any of your choices).