How Do Specialized Cells Form?

I know that cells come from other cells, but I had trouble understanding how each cell knows what type of cell it is supposed to be. I went to askascientist.org, and I learned that even though DNA is identical in every cell, not every gene that is encoded by DNA is expressed in every cell (Revollo, 2008). All cells have a set of genes that encode proteins necessary for every type of cell. Each cell also has tissue-specific sets of genes that are unique to a particular tissue or organ. For example, bone cells express bone-specific genes. The cells become specialized for a certain function during an organism's development. A totipotent embryonic cell can become any type of specialized cell, and differentiates due to cues from the environment of the nearby cells (Revollo, 2008). These cues, along with when the signals are received, instruct the cells of the embryo to differentiate.

Revollo,J.Y. (2008). How do specialized cells form? Retrieved from http://askascientist.org

Powerpoint vs. Prezi

I have always used Powerpoint for presentations as a teacher. Just recently I have discovered Prezi, which is a similar presentation tool, but with some key differences. One major difference is that Powerpoint is linear, with slides prepared in a particular order. Prezi, on the other hand, is prepared similar to a concept map or graphic organizer. There is freedom to create the map, and then decide the order you want to present. While presenting, it is easy to change the order it is viewed.

Both Powerpoint and Prezi have interesting slide transitions.Powerpoint allows you to choose how the slides transition. They can change on the click of a mouse or by themselves. Words and titles can show up in many ways as well (such as fly in, fade in, etc.) Prezi spins and zooms in on the different sections, and although the motion of it can make me feel a little bit dizzy, it really makes the information appear to be three dimensional and similar to a satellite view.

Overall, I think both Powerpoint and Prezi are similar in what they accomplish. They both present information in creative ways, but Prezi seems more interactive and exciting. If I have to choose between the two styles, I choose Prezi.