Science PowerPoint tips and tutorials

Even small graphical enhancements in drawings depicting cellular structures may have a significant impact on the overall visual perception by the audience. Membrane structures are frequently used in biomedical presentations and, if done creatively, offer an opportunity to show biological processes in a visually attractive way. Here we will describe how to generate the impression of depth and perspective using membrane receptors and proteins within the membrane plane. It may be helpful if you familiarize yourself with PowerPoint briefly by reading “Setting up your personal workspace“, “Essential drawing tools I“, “Creating customized floating toolbars“, “Essential drawing tools II“, “Drawing pentagon, hexagon and other cyclic structures“, etc.

First, we will generate the membrane bilayer using a string of beads and lines as shown in Fig. 22. Each membrane subunit consists of one circle and two thin lines, one curved to illustrate the unsaturated fatty acid component. Using copy/paste sequence and align/distribute tools, one can quickly build the necessary length of the final structure.

Figure 21. A simple model of membrane bilayer and its components.

Next, we will create several membrane rows and group them separately as independent objects. As one can see in Fig. 22, the second, third and all subsequent membrane rows do not form exact bilayers. Only the upper string of beads will be visible and such simplification will do just fine for the purpose of this exercise.

Figure 22. The collection of membrane rows ready for further assembly.

Using the arrow keys on the keyboard we will now try to position each membrane row, starting from the front, one behind the other, each time using send to back command. Rows may be organized relatively to each other horizontally and vertically. Horizontally, we placed each row to the left or to the right by a distance of half a bead. Note that each subsequent row is also shorter by one bead because this simple adjustment creates better perspective. Vertically, rows may be positioned relatively to each other using equal intervals or, for visually more pleasing effect, with linearly decreasing intervals. The difference between these two methods is shown in Fig. 23. Note that the right membrane model has more appealing look.

Figure 23. Membrane models with rows positioned with equal intervals (left), or with progressively decreasing intervals relatively to each other (right).

Using this final membrane model we next place membrane proteins and/or structures in the back of the last membrane row, as shown in Fig. 24.

Figure 24. Membrane proteins arranged for placing within the membrane plane.

Now, depending on how deep in the membrane plane we would like to place each particular protein, we may start of selecting second row or third row first, and placing it in the back using send to back command. Next we will continue selecting each consecutive membrane row behind the second or third we selected first, and send it to the back. After the last row is selected and sent to the back, we will have membrane proteins embedded in the membrane bilayer as shown in the Fig. 25. Note that one may also place particular protein deeper in the membrane plane than others. To do so, just send the selected protein to the back again after the particular membrane row you want it to be placed behind. To see this drawing process in animation with a different membrane model, see the ScienceSlides Demo 3: 3D effects in membranes on Demos page.

Figure 25. Membrane proteins placed within the membrane plane at different depth.