Protein sorting within eukaryotic cells is critical not only to typical cellular functions but also to designing new or therapeutic proteins. I noticed that students in a Physiology of Cell and Molecular Systems course had trouble with a deep understanding of the rules that guide protein sorting. In this activity, students explore protein sorting using examples from mutations that cause cystic fibrosis, I-cell disease, and amyotrophic lateral sclerosis (ALS). This activity requires students to work in groups (see Instructor Tips below) with the instructor and TA(s) circulating the room to help groups.

Pre-activity assignment
Students should be assigned the article exerpt on cystic fibrosis attached below describing how many mutations cause the CFTR transporter to not be trafficked to the correct cellular destination, resulting in disease  (or a similar article). In my class, I use Perusall integrated with our LMS (Canvas) and each student earns a small number of points for 1. Interacting with the article for >15 minutes and 2. Leaving 2 original comments/questions or replies to other students. Perusall monitors the "active" time students spend with the resource and can be set to assign a specific number of points based this set of requirements. More complex comments are given a higher score but can be modified individually. The instructor can also use Perusall to divide students into smaller groups (who only see each other's comments) for larger classes, to avoid many students commenting on a smaller resource. Lastly, the instructor can respond to any comment they choose. Grading and commenting takes about 1 hour for a class of 60 students.

This is the text that students see when they open the assignment "This paper is a summary of mutations that lead to cystic fibrosis and it illustrates how different types of mutations have different effects on the steps of getting a protein from DNA to fully functional, correctly localized protein. In the class activity, we will be thinking about how protein sorting and etc. contribute to various diseases, including cystic fibrosis. Please leave 2 comments, questions, or replies in the introduction, on the Figures, or in the text that corresponds to the Figures. Remember that short, uncomplicated comments (such as "I found this very interesting" or "Co-translational protein insertion requires an ER signal sequence.") will not be assigned as many points as more complex thoughts by the automatic grading system."

Instructor preparation
Prior to doing this activity, students should have covered co-translational protein insertion and the endomembrane system in class. The instructor should either print one set of handouts for each student or make the files available online. To prevent student groups from dividing up the work and finishing individually, only one page of the assignment should be made available at a time and nothing should be available before the start of class. For any teaching assistants or other helpers, it is useful to hold a short meeting before class in which they are given the handouts to complete as if they were the students. The instructor can then talk them through what is expected for students to get to, and address any misconceptions. This meeting can also help shape the instructor's expectations for the students. The instructor should also consider how to best form groups (no more than 4 per group) and where these groups should work in the classroom. Some students may prefer to work at the tables/desks and others may prefer to collaborate on a large post-it note on the wall, while others may prefer to work sitting on the floor. The group assignments should be given to students before the start of class to maximize problem-solving time.

In class activity
This activity was run over 60 minutes in a 75-minute class period. Students should meet their group members if they haven't already and should have the assigned paper and possibly lecture notes/a textbook available to them. The instructor will hand out/make available the first page of problems and then all instructors and TAs will circulate the room "eavesdropping" and talking to groups. The correct answers should NOT be supplied directly to groups. Instead, instructors/TAs should ask questions to guide groups towards the right thinking. After 10-15 minutes, the instructor should stop students and ask for/call on groups to provide answers to the questions on the first page. These answers should be discussed as a whole class. Then, the second page should be handed out/made accessible. After a further 10-15 minutes, these answers should also be discussed as a whole class. The instructor can ask for students to submit their work as a group for participation credit.

Analysis of activity
I analyzed student performance on 5 test questions directly related to this topic that were the same between a semester without this activity and a semester with this activity. 2 questions showed either no change or a small positive change in the percent of students answering correctly (both started with over 75% of students with the correct answer). The other 3 questions showed an increase in students answering correctly of between 10 and 30 percentage points. Notably, one question went from 45% to 75% and one question went from 81% to 92% of students answering correctly after this activity was used in class.

Summarized student comments from a Critical Incident Questionnaire with instructor responses can be found in one of the attachments. Overall, students really enjoyed the activity for its clarification of the class material, they were most engaged when in active discussion, and were least engaged when they were confused (although some amount of confusion is expected and is important for this activity to work).

I noticed that students struggled a lot more than I anticipated with the material, so that in the future I may break down some questions into some simpler parts. I felt that it was very successful and will definitely be running it in future semesters, especially since in my particular class many students have either never heard of these topics prior to this semester. There are 3 examples of student work in the attachments. I did NOT ask them to keep their first attempts, so they all look like they have the right answers, although you can see in some places where original attempts were erased or modified.