HeLa Cells

Lecture-based introductory biology courses are typically content-heavy as instructors strive to provide students with foundational knowledge in a broad range of topics.  One topic traditionally covered is cellular respiration, the series of enzymatic reactions that results in the formation of ATP, the energy currency in cells, from carbohydrates.  Cellular respiration is often difficult for students in these classes because the topic is both complex and ‘invisible’ – the students can’t observe the process.  In an attempt to overcome these difficulties and enhance student learning, we describe how the board game Mousetrap™ (Hasbro, Milton Bradley) can be adapted to model cellular respiration.  Mousetrap™ is ideal for this adaptation due to its 3-dimensionality, the necessary assembly of its 3D components and the interdependence of its 3D components. In the classroom, the pieces of the game are re-assigned into the three stages of cellular respiration (glycolysis, Krebs Cycle, electron transport chain); after each stage is discussed in lecture, students assemble that part of the board game.  By the end of class, the game is completely assembled, providing students with a workable model of the entire cellular respiration pathway.  Students then trigger the mousetrap to visualize the complete, dynamic process and ‘make ATP’ (i.e., catch the mouse).  Mousetrap™ serves as a dynamic, interactive, active learning tool that helps students build a basic, but accurate model for cellular respiration that can be used as a scaffold for subsequent upper-level courses or for more complex discussions related to fermentation, toxicology, and/or enzymatic regulation. 

This module contains exercises designed to help students understand how solute concentrations affect the direction and rate of osmosis. Students are given different scenarios to predict the direction of water movement, calculate the rate of change in mass and create graphs to determine the isotonic concentration.

This module introduces activities that allow students to walk through the cell cycle and mitotic cell division processes. As part of the activities, students learn about and apply knowledge of chromosomal behavior to identify different stages of mitotic cell division in plant and animal cells. They also calculate and compare mitotic indices for normally dividing and cancerous cells. Students apply quantitative and statistical concepts such as sample size, mean, standard deviation, and standard error of the mean to discuss the impact of sample sizes on interpretation of biological data (i.e., normally dividing and tumor cells, in this case).

Cell division is a key concept in cell biology. While there are many popular activities to teach students the stages of mitosis, most make use of simple schematics, cartoons, or textbook diagrams. Others engage students in acting out the stages, or modeling them with physical objects (i.e. noodles, pipe cleaners). These approaches are useful for developing student knowledge and comprehension of the stages of cell division, but do not readily convey the real-life processes of mitosis. Moreover, they do not teach students how cell biologists study these processes, nor the difficulties with imaging real cells. Here, we provide an activity to reinforce student knowledge of mitosis, demonstrate how data on mitosis and other dynamic cellular processes can be collected, and introduce methods of data analysis for real cellular images using research-quality digital images from a free public database. This activity guides students through a virtual experiment that can be easily scaled for large introductory classes or low-resource settings. The activity focuses on experimentally determining the timing of the stages of cell division, directing the attention of students to the tasks that are completed at each stage and promoting understanding of the underlying mechanisms. Before the experiment, the students generate testable predictions for the relative amount of time each step of mitosis takes, provide a mechanistic reason for their prediction, and explain how they will test their predictions using imaging data. Students then identify the stages of cell division in a curated set of digital images and determine how to convert their data into relative amount of time for each phase of mitosis. Finally, students are asked to relate their findings to their original predictions, reinforcing their increasing understanding of the cell cycle. Students praised the practical application of their knowledge and development of image interpretation skills that would be used in a cell biology research setting.

This module introduces the exponential growth of cells in the context of understanding cell division. It is intended for an introductory biology audience.

Traditionally-trained undergraduate students often lack an understanding of science as an active process that yields the information presented in their textbooks. One result has been a call for more research experiences built into traditional introductory undergraduate courses, now commonly referred to as course-based undergraduate research experiences (CUREs). The laboratory module presented in this paper used an established four-step pedagogical framework to simplify and streamline the development and implementation process of a CURE in an introductory biology laboratory setting. A unique six-week CURE was designed for undergraduates enrolled in a cell biology lab that employs Saccharomyces cerevisiae as a eukaryotic model organism. Students address a research problem that is of interest to the scientific community: Do select chemicals in the environment have adverse effects on the mitotic cell division? Students are first introduced to S. cerevisiae, its life cycle, morphology, growth curve generation and analysis, and the laboratory techniques required to cultivate this organism. Working in groups, students then act as scientists to research primary literature, ask an original question, develop a testable hypothesis, collaborate with peers, design and conduct an experiment, analyze and interpret data, and present their work to their peers. In addition, students are involved in multiple levels of iterative work, including addressing problems or inconsistencies, ruling out alternative explanations, and/or gathering additional data to support assertions.

Photosynthesis is a process by which plants synthesize glucose and oxygen in presence of sunlight through light dependent reactions by utilization of sunlight, water to synthesize oxygen, ATP and NADPH and light-independent reactions to synthesize carbon dioxide and carbohydrates. Cellular respiration is a metabolic pathway that breaks down glucose through glycolysis, pyruvate oxidation, citric acid / Krebs cycle and oxidative phosphorylation. Primary producers produce energy and consumers derive energy from primary producers. Primary productivity is the accumulation of energy in form of biomass. Integrating biological science and mathematics helps to understand how differential regulation of factors impacting metabolic pathways and processes impact primary productivity.

Osmosis is a process by which by which solvent move from a region of lower solute concentration to region of higher solute concentration through a semi-permeable membrane. Cells utilize the process osmosis and osmotic pressure to transport substance in and out of the cell cytoplasm. Solution is made up of solute and solvent - concentration of a solution is the measure of the amount of solute that has been dissolved in a given quantity of solvent or solution. Spectrophotometer can be used to measure the optical density of the solution which relates to the change in concentration of the solution. As the concentration in any biological system will change the cells shape, size and number will change in that micro-environment.

With a veritable myriad of cell parts to cover, it is easy for educators to become locked into marathon presentations that become taxing for both the instructor and the students. While we hope and expect that students master this material, the disconnect between this material and its practical value often encourages students to tune out. How can we cover this topic with the depth and breadth it deserves while simultaneously engaging the students? How can students learn the subtleties of the cell when each part is a world unto itself? Here I explain how educators can accomplish these goals using the “Cells: A World A Part” activity. In this activity, the class is divided into several teams that are each assigned a particular cell part. Guiding questions help students assess their current knowledge about their cell part so they can build on that knowledge using a constructivist approach. Students explore recent scientific literature, ask thought provoking questions, and propose experiments to address some of the enduring mysteries about their assigned cell part. As they work, students develop teamwork and time management skills; they also come to appreciate cell biology as they learn its real-world implications and discover how these cell parts relate to human disease. The climax of this activity is an exciting presentation session that enables students to showcase their scientific communication skills as they share their newfound knowledge with their classmates. 

Here is a short video describing this Lesson:

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Lights, Camera, Acting Transport! is an active and unique role-play exercise designed to teach introductory biology students basic concepts of passive and active membrane transport. The activity involves three acts in which students, representing various molecules, ions and components of the plasma membrane, interact to learn the fundamentals of passive transport, primary active transport and co-transport across cellular membranes. This activity was designed in response to observations that many students struggle to understand the basic principles of membrane transport. After consistently observing high levels of student engagement and enjoyment from this activity, we assessed student learning gains from, and attitudes towards, this exercise. Student understanding of membrane transport significantly improved after participation in the activity, and these improvements were largely retained over time. Moreover, students reported positive attitudes towards the activity in terms of perceived learning and enjoyment, and participation in the exercise significantly increased student confidence. We conclude that this activity constitutes an effective and enjoyable instructional tool that appeals to a diverse population of students.