Tag: science

Jurassic Park: Web of Issues

Web of issues for the movie Jurassic Park.

Well we watched Jurassic Park last night and concluded it with a discussion about the issues underlying the movie, the same way we’ve been studying analyzing the issues underlying texts. Discrimination based on race and obesity came up first (the fat guy and the black people “always” die), but I was able to coax a bit of discussion about the role and responsibility of science and scientists. Our discussion is summarized in the graphic organizer above, but there are many more subtexts to the story that we did not have time to explore.

Jurassic Park by Michael Crichton (the book).

I like both the movie and the book because, like most good science fiction, they explore some interesting issues that relate quite nicely to the curriculum. Jurassic Park has a nice little introduction to DNA and gene sequencing that is tied to some the history of life on Earth. As works of art in their respective fields, however, I prefer the movie. The novel has a lot of wonderful detail, and the scientist in me loves the detail, but the characters are not as well drawn and the story seldom strays from its main thesis, scientific hubris. What it has to say about that issue is well expressed and well researched so it does capture the interest of the reader. (The follow-up book, “The Lost World”, sails adrift of the science, is logically incoherent and has a proportionate deterioration in the quality of the writing.) I do however recommend the original Jurassic Park book to my students as a personal novel.

Steven Spielberg makes a great movie, extracting empathetic performances from the actors. Since the book’s author, Michael Crichton, also wrote the screenplay, the movie stays true to the core issues in the text. I think its a great example of a successful, dare I say synergistic, collaboration.

Tomorrow, instead of retelling around the issues in writing, my students are going to try to do so in a skit. This could get interesting.

Microscope photography!!!

Algae and amoebas at 400 times magnification.

Did you know that if you hold up a regular digital camera up to the eyepiece of a microscope you can take a great picture of a magnified slide! I didn’t. And I really didn’t think it would work when I tried it, but the results are remarkable. With a somewhat steady hand you can also make decent animations.

If you look carefully you can see the amoebas zipping around. I also have a really cool larger version too, which shows the entire slide..

I’ve never been very good at identifying things (I’m a lumper not a splitter) so all I think I can say for sure is that there are algae and protozoans in the picture. BiologyCorner has a nice identification guide for organisms usually found in ponds, which is part of one of their lessons, Biodiversity of Ponds.

Toilet Paper Timeline in practice

Who thinks they're at the most important event?

The Toilet Paper Timeline of Earth History worked as well as I’d hoped. The beginning was a bit boring, it was a challenge keeping the kids focused, since nothing much happens for a very long time. It helped that we had to unroll the toilet paper back and forth across the room, so I had a different student take over every time we had to turn around.

That was not quite enough though to keep them from getting distracted, however, so I also assigned people to stand at the location of major events. This worked out nicely in the end because it let me ask them, at the end, whose event was the most important? Most of them made some argument without any prompting; the group is already pretty comfortable with each other and are not afraid of speaking up.

During the unrolling, most events occur in the final two turns. Students did notice this fact, which is the ultimate point of the exercise. Getting them to talk about different events, like the time of the first multicellular organisms or the extinction of the dinosaurs, helped students own the work. All together, it seemed to strike their imaginations.

They also seem to like using Cartoon History of the Universe as their reading assignment.

The Pre-Cambrian. Nothing much happens for a long, long time.

Toilet Paper Timeline of Earth History

Image from Wikimedia Commons.

Jennifer Wenner has posted a beautiful demonstration of geologic time using toilet paper for the timeline at SERC. You’ll need a 1000 sheet roll and by the time you’re done there will be toilet paper everywhere.

This is a great demonstration because as you unroll the toilet paper you get a great feel for the long spans of time in the preCambrian when nothing much happens, and then, as you approach the present, events occur faster and faster. There’s 300 million years between the formation of the Moon and the formation of the Earth’s atmosphere. That’s 60 sheets! while modern man only turns up about 10,000 years ago, which is 0.002 sheets; about the width of the line drawn by a pen. Even the dinosaurs went extinct only 14 sheets from the end.

The SERC webpage has a spreadsheet with most of the important dates marked and translated into toilet paper units. The Worsley school in Canada has some nice pictures of the toilet paper being rolled out all the way down the hall.

History of life on Earth timeline (from NASA).

Living without oxygen

Microscope image of the undescribed species of Spinoloricus (Loricifera; stained with Rose Bengal) (image from Donavaro et al., 2010)

While there are quite a number of single-celled microbes that live in environments without oxygen (they’re anaerobic), multicellular organisms have now been discovered, living near the bottom of the Mediterranean Sea, that also do not need oxygen.

(a) a hydrogenosome-like organelle. (image from Donavaro et al., 2010)

What’s really neat, and creates a great teaching point, is that these anaerobes don’t have mitochondria in their cells, so they can’t use oxygen for energy:

The creature’s cells apparently lack mitochondria, the organelles that use oxygen to power a cell. Instead they are rich in what seem to be hydrogenosomes, organelles that can do a similar job in anaerobic (or oxygen free) environments. – Vogel, 2010.

The conclusion paragraph of the journal article, would make a nice piece for students to mark up and process. It might even work better for use on a vocabulary test because you’ll need to understand the vocabulary to understand the text.

This is the first evidence of a metazoan life cycle that is spent entirely in permanently anoxic sediments. Our findings allow us also to conclude that these metazoans live under anoxic conditions through an obligate anaerobic metabolism that is similar to that demonstrated so far only for unicellular eukaryotes. The discovery of these life forms opens new perspectives for the study of metazoan life in habitats lacking molecular oxygen. – Donavaro et al., 2010)

Possible endosymbiotic prokaryote and hydrogenosome-like organelles. (from Donavaro et al., 2010)

The article, by Donavaro et al., (2010) also has an intriguing image of suspected “endosymbiotic prokaryotes”. Some organelles in cells are believed to have once been separate organisms that developed symbiotic relationships with their host cells. It’s nice to see an example of it in real life. Even if it’s a bit hard to interpret.

The ultimate implication of this discovery, is that there are probably a lot more anaerobic environments on other planets so the chances of finding extra-terrestrial multi-cellular life might not be as low as we’ve thought.

DNAi: History of genetics and manipulating DNA

DNA. (from Wikipedia)

DNA interactive is another great resource for studying the history of genetics and how we manipulate and use it today (recommended by the indispensable Anna Clarke). They have lesson plans and nice pages on the modern techniques used to work with DNA.

Image from the DNAi webpage on gel electrophoresis. Electrophoresis is a bit like chromatography which might make for a good demonstration.

I have not done much with genetic sequencing myself and I found the website interesting and informative. I have, however, written programs to get and work with the GenBank database, which is not that hard since they have some easy tools to work with. I would love to figure out how to get a sample sequenced and then run it through GenBank to identify it. It would so nicely integrate the curriculum, using a practical exercise to solve a problem (like what species are on the nature trail), while using the same tools and resources that scientists use, and tie wonderfully into the short stories in Mirable.

CellsAlive: Cell model

Interactive cell model from Cells alive!

Another good interactive cell model, similar to the Teach.Genetics‘ Flash app I posted about earlier, can be found at CELLS alive. I first used the CELLS alive website two years ago and I like it because, while it has a much simpler picture than Teach.Genetics’, it has a nicely linked glossary of terms. The glossary is, however, a little technical, but it’s a nice exercise (and not terribly difficult) for students to decipher the basic information that they need.