Onion Mitosis Lab

One of the labs that I've come to enjoy while we are studying the cell cycle in AP Biology is the Onion Mitosis lab. I love this version of the lab because it requires very little prep time on my part, and within a week, my students have some real data to analyze. The lab I use with my students was modified from Lee Ferguson and can be found on her website, The Biology Space, here under the cell structure and function resources. 

It's hard to see, but we usually hold the onions up in the beakers by rubber banding them around a straw that sticks lower than the ends of the onions. That way the root bases aren't pushed against the bottom of the beaker.

I really only modified the materials that I provide the students to experiment with and how the results will be presented--since my students do a mini poster presentation of their results. The modified lab document can be found here.

Modeling Checkpoints in the Cell Cycle

I am always trying to find ways to make the concepts we talk about in AP Bio come to life (no pun intended), especially during the first 6 units which deal primarily with molecular biology. In class, we were working on the cell cycle, focusing on the three checkpoints and the cell regulating itself so the process of making more cells doesn't go awry. Late one night an idea popped into my head, so as my husband was trying to go to sleep, I was busy scribbling notes for a new activity on a post-it note (as seen in the picture below).

 I was thinking about all the cyclin production for the checkpoints and it reminded me of the competitions I've seen in some reality TV shows. On several occasions, a team has to fill some container with water/oil/sand before they can move onto the next part of the competition. It made me think of cyclin reaching a critical level before the cell moves onto the next part of the cell cycle. 

I had had enough of water messes with the labs I've done with my physical science class this year, so I couldn't bring myself to do a race that included sloshing water. Then I remembered that my classroom has inherited an unusually large number of cotton balls, so many that I'm fairly certain we can do the respirometer lab for another 100 years without needing any more cotton balls. As a result, cotton balls represented cyclin. I put together cards for each job in our cell cycle model. It begins with organelle drawing to represent the G1 phase of Interphase as the cell is growing/maturing. At the same time the first cyclin producer is adding "cyclin" cotton balls to a bucket to represent the buildup of cyclin in the cell. Once enough organelles were present and the cyclin had reached a critical level (up to a piece of tape on a bucket), the cell could move onto the next part of the cell cycle. Here the DNA was synthesized. We just had two pop-bead chromosomes that had to be replicated exactly. While the DNA was copied, a second cyclin producer was working on filling the bucket to the critical level. 

If both the DNA replication completed correctly and the 2nd cyclin reached the critical level, the cell would move onto M phase through anaphase. Again, once the critical cyclin level was reached, the cell moved on, completing M phase and going though cytokinesis. And the process could continue. Also during this process, there was a cell cycle checker to make sure the cell was going through the cycle correctly and would halt cyclin production and therefore the cell cycle if anything went wrong. They could then send the cell into G0, its non-dividing state.

The link to the job cards is here.

Cancer Project: Being a Patient Advocate

Just a few weeks ago, we finished our unit on the cell cycle.  The unit culminates with students presenting information on a certain cancer that they have researched.  We've done this project for two years now, and each time I feel like something is missing. I don't like to ask students to do work without a purpose--either to help them understand concepts in the class more deeply or to teach them a skill that will serve them beyond the AP Biology classroom.  This project was hardly doing either. Last year, I modified the project slightly, but after this year's presentations, I finally decided on the purpose of this project.  Instead of just presenting information on the cancer, students are going to become patient advocates.  They'll be researching information that would be helpful for a friend who is going through a cancer diagnosis.  When they are adults and face a health crises or someone close to them does, it will be helpful for them to know how to advocate for the patient.

In the past few years, I have had a few friends receive cancer diagnoses. There are two in particular who stand out to me.  One remained fairly passive in the process, didn't ask questions, and wasn't active in seeking treatment.  The result was tragic.  My other friend did incredible amounts of research, had active discussions with her doctors and chose her doctors and treatments with full knowledge of risks and rewards. Her outcome has been far more positive. I want to equip my students to make informed decisions about their health and be able to help others to do the same. Of course, knowledge doesn't guarantee a good outcome, but knowing how to find the information beforehand can be a huge help.

I've embedded the information and rubric I give students, and a link to it is here. I also have a Google Form that I use to evaluate students' projects as they are presenting. I merge that information into a feedback document for each student.

Modeling Mitosis with Oreos

Yesterday we did another one of my favorite "labs" in biology.  The students had just read the mitosis and cell cycle chapter.  To review the events of mitosis, we do an activity I found on Amy Balling's blog, Ballin with Balling. She talked about giving her students an engaging activity on the last day before Christmas break.  This involved pulling off the tops of double stuffed Oreos and using sprinkles, toothpicks and the cream covered half of the Oreos to model the process of mitosis and cytokinesis.

Her blog post also included a link to the lab sheet she designed to go with the activity.  I used her lab sheet, but reformatted it to be only two pages long.  Here's the reformatted version.

It has been a big hit with the students both years that I've used it.  It's one of the few opportunities that students have to eat their lab.

Introducing the Cell Cycle

Last year I found a lab that worked perfectly for introducing the cell cycle unit.  It was on Darci Harland's blog STEM Mom, titled Engineering Cell Division-a NGSS Lesson. I didn't even reformat it--just printed it as is.

I laid out a box of random supplies such as yarn, string, beads, pipe cleaners, play dough, modeling clay, and gummy worms.  The gummy worms just add an element of fun.  I think they look like chromosomes, but my students usually use them for something else in the cell. They happily eat the worms when they finish the project.

We do this before they even start taking notes on the mitosis and meiosis chapters.  As they work through the design and questions, we can talk about what they are realizing has to happen in a cell before it can divide.  It's so much more than just making a copy of the DNA.  This activity also gives me something concrete to refer back to as we delve into the details of the cell cycle.