Mitotic and Meiotic Chromosome Movement Demonstration

What is the strategy?

At George Mason University (GMU) all biology majors must take and pass cell biology (Cell Structure and Function) with a grade of C or better prior to taking genetics.  Students are introduced to the cell cycle and meiosis in their cell biology course, however, many students enter class with misconceptions about the cell cycle and meiosis.  Some of these misconceptions or misunderstandings include mitosis makes up the entire cell cycle; accurate depiction of chromosome movement during mitosis and meiosis; the difference between mitosis and meiosis.  The genetics course offered at GMU begins with the cell cycle and meiosis and if students do not have a firm understanding of the topics, they can quickly fall behind.  For this reason, we developed a two-part activity that will increase understanding of these two challenging concepts.

Part I. In-class assessment worksheets

The worksheets contain a series of questions on the cell cycle and meiosis to be used in the cell biology course.  Prior to the lectures on the cell cycle and meiosis, students will complete an in-class pre-assessment worksheet.  Immediately following the lectures, students will complete an in-class post-assessment worksheet.  The pre- and post-assessment worksheets will include the same questions.  Students will not receive a grade for either assessment; they will receive 2 points for completing both worksheets.  Pre-assessments will be handed out, collected and scored by a GMU Learning Assistant or Noyce Fellow.  Learning Assistants are students who have taken and performed very well in the course while Noyce Fellows are students who were former Learning Assistants who have an interest in K-12 teaching careers.  The Noyce Fellows will receive their Bachelor’s of Science in Biology and their Virginia State teaching license upon graduating. 

Part II. Chromosome movement during mitosis and meiosis

As the in-class lectures continue, students will have an opportunity to voluntarily participate in an activity outside of class that will reinforce their understanding of mitosis and meiosis with the use of magnetic beads to depict chromosome movement.  The Learning Assistant or Noyce Fellow will facilitate the sessions.  During the sessions students will receive a brief review of both concepts (mitosis and meiosis).  They will then be asked to demonstrate chromosome appearance at specific stages of mitosis and meiosis.  The sessions are offered before the post-assessment worksheet is given.

Why should I use it? (How are they useful for the students? How are they useful to the instructor?)

The worksheets will allow the instructor to determine the level at which students actually grasp key concepts involved in the cell cycle and meiosis.  Based on the scoring, the instructor can review key concepts students missed or did not understand completely. 

What is an example (or two) of the task?

Part I: In-class assessment worksheets

The in-class assessments are divided into four sections: definitions, describe a key event at each stage of the cell cycle, identify stages of mitosis (images are provided) and draw chromosome arrangement at three different stages of meiosis (stages are provided).  There is an increased level of complexity as students move through the four sections. 

Part II: Chromosome movement during mitosis and meiosis

The sessions will begin with a brief discussion on chromosome definitions (sister chromatid, homologous chromosome, etc.) as well as an overview of mitosis and meiosis.  Students are then asked to depict the appearance of chromosomes (using magnetic beads) during each stage of mitosis and meiosis.

How do these tasks fit into my class?  How long will they take?

Students will complete the pre-assessment worksheets prior to the start of lecture; they will receive 15 minutes to complete the worksheet.  They will then be invited to participate in a chromosome movement activity as the class delves into lecture material on the cell cycle and meiosis.  The chromosome movement activity will take about two hours to complete.  The post-assessment worksheet will be completed after the lectures on the cell cycle are presented; students will be given 15 minutes to complete the worksheet.

Should I do these problems in groups?  How big?  Who chooses them?

We have designed the series of activities to have students work independently. 

For which topics should I assign them?

The series of activities described focus on two topics only, the cell cycle and meiosis.

How should I grade these problems?  Should I grade these problems?

The pre- and post-assessment worksheets are not official included in the student’s overall course grade.  All students are given two points for completing both worksheets; the points will go towards their final grade. 

What pitfalls do I need to avoid?

One major pitfall I have to avoid is giving students a false sense of confidence in understanding the topics.  I have to point out that the chromosome movement sessions are provided to enhance their understanding and should be used as an additional study tool; the sessions should not be used to completely replace their normal study routine.

What do I need to explain to my students about this new classroom activity?

The instructor should give a brief explanation of the in-class pre- and post assessment worksheets.  The instructor should also mention the worksheets should not be confused with quizzes and do not count towards any lecture exam.  The worksheets are designed to gauge students’ understanding of the lecture material.  The instructor should also explain the material discussed is a major portion of their genetics course (the course which should be taken after cell biology).