The expression of genes is influenced by how the DNA is packaged in chromosomes, in a structure called chromatin. Base modifications can be involved in packaging, with regions that have low or no gene expression usually containing high levels of methylation of cytosine bases. Well, what if we wanted to figure out what gene is responsible for being able to digest milk. Well, one thing that we can do is if we have an idea of what gene it might be we can just knock-out that gene. So let's just imagine that there's a gene here and we imagine that this has something to do with the digestion of milk. Sep 28, 2013 · (OLD VIDEO) DNA Structure and Function Amoeba Sisters. Loading... Unsubscribe from Amoeba Sisters? ... Gene Regulation and the Order of the Operon - Duration: 6:16. DNA Structure During the 1950s, a tremendous explosion in biological research occurred, and the methods of gene expression were elucidated. The knowledge generated during this period helped explain how genes function in microorganisms and gave rise to the science of molecular genetics. RNA polymerase (the enzyme that builds an RNA chain) binds to the promoter, a DNA sequence that signals the gene's start. Elongation (transcription) RNA polymerase moves along the DNA template strand in a 3′-to-5′ direction, adding nucleotides only to the 3′-end of the growing RNA molecule.