ABSTRACT
It is difficult for students to conceptualize biochemical processes that are portrayed as two-dimensional figures in a textbook. One of the most difficult tasks for science teachers is to explain concepts that cannot be seen with the naked eye or even with a standard classroom microscope. Students develop some sort of personal and often incorrect conception of these processes. Good science teachers use models to explain the invisible. This allows the teacher to assess and guide students' ideas. On completion of the lesson, students should be able to describe the location and properties of DNA, the process of transcription and translation, and the role enzymes play in protein synthesis. The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes and replicated. Each DNA molecule in a cell forms a single chromosome.
