Chromosomal Ride

I realized when I was doing the Blogging 201 class last month that my blog’s tag line, “The Brain–is wider than the Sky,” is not well explained.

Aside from the fact that the tagline is taken from an Emily Dickinson poem and is therefore supposed to be–ahem–literary, my original idea for using that tag line was to write as a neuroscientist, a person who studies the brain.

I earned a PhD in Neuroscience in 1993 from Stanford University. Since then I have taken a circuitous ride through different jobs in science, including a postdoc at Caltech, a stint in the biotechnology industry, another role in academic project management, and am currently employed in science education and outreach. I teach with an educational non-profit called Science from Scientists, which was founded in the Boston area where I used to live, but has recently opened an office in the SF Bay area.

Giving a presentation to a group of 7th grade students.

I discovered an interest in teaching when I had children and taught them in Sunday School and in Girl Scouts.  I feel like hands-on science education is more play than work. It brings me back to why I wanted to become a scientist in the first place.

Up until now, though, that interest hasn’t been reflected very much in my blog. So I’m going to try to remedy that with an occasional series of posts on scientific or science education topics that I’ve taught recently, or just topics that interest me.

This first blog on a science topic doesn’t have a lot to do with the brain per se, but it does have to do with cells: Mitosis.

Mitosis is the process of cell division, in which one cell divides into two daughter cells. I first learned about mitosis more than 30 years ago. I loved high school biology. Then I took AP Biology and then went on to be a Biology major in college. I considered myself a nerd because of this rather obscure interest. But when I was preparing to teach this lesson, I suddenly noticed mitosis everywhere.

A friend posted this red and green Christmas-y gif video to her facebook page. I believe it is a dish of cultured pig kidney epithelial cells stained with fluorescent dyes. It is sped up several-fold.

The red color is the DNA, the chromosomes that first exist diffusely in the nucleus, and then duplicate, condense, and line up at the “50-yard line” in the center of the cell during metaphase. The green color is tubulin, a protein that forms the tubules that pull the chromosomes apart. The gif is on a loop, you can see the same cell dividing over and over again, and then the one above it starts but doesn’t quite get to finish before the loop starts over.

It’s hard to track down the source of this image. Not only is it on Facebook, it’s on reddit, it’s on imgur, it’s on giphy. It gets a boatload of praise in the online comments.

Then I heard some high school students discussing mitosis in Starbucks, right before Christmas. They were decidedly less impressed than the reddit commenters. They seemed to have a midterm exam on the subject, which did not endear it to them. The names of the phases don’t really help, either: interphase, prophase, metaphase, anaphase, telophase. And then: cytokinesis! Gee, I can’t imagine why your average high school student in Starbucks wouldn’t think this is extremely cool.

In any case, mitosis can be observed especially well in an onion root tip. For my lesson, I was instructed to put an onion in some water and let it grow roots.

Our classroom set up

I tried 3 different onions. The only one that actually grew roots was an old red onion I had sitting around in the kitchen that I had bought from Trader Joe’s. I bought two more from Safeway that didn’t grow roots at all. I wonder if they’d been treated with something to prevent root outgrowth.

From these root tips, the students could try to make their own slides or, more practically, they could observe the phases in commercially prepared slides under the microscope.

Phases of mitosis in the onion root tip. Image credit: Carolina Biological Supply

It turned out that this observation activity took most of the class, but the students enjoyed using the scopes even if not too many of them could make their slides.

The biggest coincidence was when I attended my husband’s company holiday party at the Exploratorium, the big Science Museum in San Francisco. We got our appetizers and wine (served charmingly by young people in lab coats and Einstein fright wigs) and found a seat across from the Microscope Imaging Station. I looked up from my goat cheese tart and what did I see there, but the phases of mitosis as seen in an onion root tip?
–Hey, I have one of those right now, growing in my kitchen!

Microscope Imaging Station at the Exploratorium, San Francisco

Then I found this rap video on YouTube:

Mitosis, chromosomal ride
Inter-, pro-, meta-, ana-, telophase, divide
Eukaryotes go from one cell to two,
Mitosis, how cells renew.

There is a *lot* of information there, Mr W. There is way more information than my students need to know at this age. But at least it’s pretty memorable. And I told my students to go to the Exploratorium over Christmas break. We didn’t have this kind of thing back when I was learning it!

I think everyone, even those teenagers in Starbucks with their peppermint mochas and caramel macchiatos, should know at least a little about mitosis. It’s going on in your body every day, all the time. When it goes awry, you can get tumors, but that it happens correctly so often is a miracle indeed.

9 thoughts on “Chromosomal Ride”

  1. “… but that it happens correctly so often is a miracle indeed.”

    It is quite amazing— billions of good cells produced over relatively short amounts of time. Nature always astounds us humans when we actually look at it.

    Liked by 1 person

  2. Terrific blog! Love the science stuff. I’m forwarding this to my 10th-grader right now. She was complaining about this very thing last night as she studied for a test. Serendipity abounds. 🙂

    Liked by 1 person

  3. That gif is mesmerizing!!! I recently have been reading much on DNA. Mitosis and biology in general is so interesting – I often wonder if my teachers in the sciences had been different if that is where I might have ended up. Teachers are so so important.

    Liked by 1 person

    1. Great! I’m glad it is easy to understand. I’m planning to write about the process of researching and preparing the lessons as much as just presenting the lessons themselves. I started teaching later in life so there is a learning curve for that too, which I think is fun to write about.

      Liked by 1 person

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