#662 DNA

DNA is a molecule that does two things. First, it acts as the [1] material, which is passed down from generation to generation. Second, it directs, to a considerable extent, the construction of our bodies, telling our cells what kinds of molecules to make and [2] our development from a single-celled zygote to a fully formed adult. These two things are of course [3] . The DNA sequences that construct the best bodies are more likely to get passed down to the next generation because well-constructed bodies are more likely to survive and [4] to reproduce. This is Darwin's theory of natural selection stated in the language of DNA.