I think, by using one or another kind of analogy - that is, representing each new thing as though it resembles something we already know.
Analogies allow students to think about complex and abstract subjects in simple or familiar terms.
Use of an analogy provides a bridge to access the abstract concept. The cell membrane is the gatekeeper, the Golgi apparatus the packaging department, the mitochondrion a power plant, and the lysosome is the suicide sac or stomach of the cell. There are many analogies that teachers have developed to represent the process of protein synthesis. Teachers may adapt this pedagogical strategy to any analogy that works for the abstract idea that is introduced. Talk about Frieda, the boss who sits in her office all day handing out recipe cards to messengers who go out to the various assembly stations on the factory floor and direct the assembly of ingredients that correspond to the recipes.