I wanted students to be able to answer this question: If every cell in the body has the exact same DNA, then why do cells look different and do different jobs? Why are muscle cells long and stretchy while nerve cells are web-like, yet they have the same set of directions inside?
To answer this question students needed to understand that genes can be turned on an off. Even though every cell in the body has the same DNA, cell types only read the genes that apply to them. Eye cells only read and use eye genes, skin cells only read and use skin genes, etc. So how do specialized cells know which genes apply to them?
I created an activity that likens the genome to the blueprint of a house. A house blueprint includes all the information needed to build the house- the electrical, the plumbing, the framing, it’s all there. When the electrician shows up to install the wiring and outlets, he only needs the information on the blueprint that applies to him. The same goes for cells.
Each student will scan through the DNA looking for their specific promoter sequence. Once they find it, they begin the transcription and translation process until they reach a stop codon.