Academic journal article The American Biology Teacher

The Story of the Calvin Cycle: Bringing Carbon Fixation to Life

Academic journal article The American Biology Teacher

The Story of the Calvin Cycle: Bringing Carbon Fixation to Life

Article excerpt

As biology teachers and professors, we aim to prepare our students to think critically and analytically, and to provide a set of conceptual and practical skills the students will need to continue their education in biology during and after their college years. Another of our general goals in teaching a biology class is to convey to our students our interest and excitement about science, and biology in particular. This is not an easy task, especially in required introductory courses or less popular plant biology courses, as student motivation is usually lacking. Since most biology students think of plants as inherently less exciting than animals, getting students excited to learn something about physiological processes in plants is especially challenging. Add to that the difficulty in visualizing complex biochemical steps, and the introductory biology student, biology major or non-science major is ready to throw in the towel.

Many instructors of biology have noted that "students frequently have trouble visualizing what happens in a cell" (Chinnici et al., 2004). Techniques that require active participation to work out the details of a sub-cellular process help students visualize and understand abstract concepts better. Examples include hands-on exercises that require building and using a model (see Stavroulakis, 2005), or role-playing (Chinnici et al., 2004). In my introductory courses, I have resorted to role-playing and biological "plays" to help students visualize more abstract subjects in a manner that is easier for most students to understand. This is especially true for the inexperienced science students, especially first year or non-major students. An example is The Story of the Calvin Cycle, described here, in which students trace the biochemical steps of the Calvin cycle through a musical play. Although introductory textbooks such as Campbell and Reece (2005) and Tobin and Dusheck (2005), and plant biology texts such as Graham et al. (2006) and Rost et al. (2006) provide beautiful diagrams showing the biochemical steps of the Calvin cycle, a review of these diagrams is just one passive step used in my classroom. Through the role-playing exercise described here, students will use reading, seeing, hearing, and physical participation to learn the subject and, as suggested by Chinnici et al. (2004), this combination ultimately enhances learning.

In my classroom, the details of the Calvin cycle (formally the Calvin-Benson-Basham cycle) are presented after a general discussion of the big picture of photosynthesis in the global ecology of the planet. By the time the students are focusing on the chemical reactions in the Calvin cycle, they have studied the overall goals of photosynthesis and its role in the Carbon cycle. They have also reviewed, through various activities, the photochemical reactions of photosynthesis leading to the production of ATP and NADPH and are ready to find out the details of how these products are used. This way, we understand why the Calvin cycle is dependent on the "light reactions" and why we do not refer to the Calvin cycle as the "dark reactions."

Learning Objectives

To understand:

* the three major steps of the biochemical reactions in the Calvin cycle

* the significance of Rubisco to the process

* the significance of carboxylation to the plant

* the importance of regeneration to the cycle

* the relationship between the Calvin cycle and the products of the photochemical reactions

Pertinent Vocabulary/ Background

(Mauseth, 2003; Taiz & Zeiger, 2002)

Materials Required

This exercise requires the willingness of the students to participate in the musical. Not much else is required. Due to my general enthusiasm for biology, and all of the other biological plays and activities I employ in teaching, my students are used to and expect active participation in learning a complicated process such as the biochemistry of the Calvin cycle. …

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