Looking for some activities to jazz up your class lecture on the cell and biology?  Here are a few hands-on teaching activities for middle school or high school:

Here are some cool cells to look at under a microscope:

• Cheek cells
• Onion cells
• Thin smears of ripe versus green banana, stained lightly with iodine.  Says Karen Kalumuck:  “You should see sickle-shaped structures that are amyloplastics – starch storage organelles.  You’ll see more of these in one of the types of bananas than the other, and can correlate with taste.  Predict which banana will have more darkly staining amyloplasts?  What happens to the starch?
• Compare tomato cells with pulp cells.  The skin cells are bricklike, providing structure, whereas the pulp cells are like balloons, to store starch with the lowest surface area to volume ratio.

No access to a microscope? Check out the Exploratorium’s Microscope Imaging Station — you can see videos of sea urchin cells dividing, stem cells, a zebrafish heart cell beating, and more. Any of the images here can be used in educational settings.

You can also build a cell model, and “scale up” cell and organelle dimensions to human scale.  If a cell was the size of my head, how big would a mitochrondria be?  Or, build a 3D diaorama inside a shoebox.  One teacher uses the analogy of a school — the nucleus is the principal’s office, the DNA is the school files, the teachers are the ribosomes, the students would be proteins, and the school bus is a vesicle.  Or, list a set of different analogies (the cell is like “The Simpsons”, the cell is like “a city”)  and let students choose, and make their set of analogical functions.

You can also model a cell membrane using soap film. You can stick a wet finger through a bubble film, just like plasma membranes are selectively permeable.   See this activity here.

This Traits of Life website at the Exploratorium has a set of online interactives and downloadable posters and articles.

You can do a play or drama about the cell — here’s an example about the Immune System from our teaching tips podcast.

Create a bingo or board game where students read off the functions of the parts of their cells, and then place those parts on the cell diagram.

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Ok, it probably wouldn’t be very yummy, but here’s another hands-on activity you can use that’s rather Halloween-like.  Called “Make a ‘mummy’”, this Exploratorium activity is a great way to demonstrate how mummification works, by drying out the tissue in a fish using baking soda.  Egyptians used a specific type of salt to do this, but baking soda will do the trick, giving you a tough leathery fish.

If you’d just left your fish out on a shelf, exposed to the air, bacteria and fungi would have begun to decay the fish, creating strong, unappetizing odors. Since all living things require water to survive, removing the water from the fish greatly inhibited the growth of these organisms, decreasing the unpleasant effects of rotting.

For an inquiry activity, try substituting salt for baking soda. Which one works best?  (Hint:  It’s not the salt).

Make him a little pyramid home. Imagine his little fishy afterlife.  Bury some fishy mummy friends for him to play with.

From Platonides on Flickr

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I was recently reminded of this wonderful visualization of the processes inside the cell.  As a physicist, I found this quite powerful in imagining this mysterious (and usually, to me, boring) microscopic world.  It was created by a Harvard professor in conjunction with a scientific animation company.  Here’s the video:

In my art and science visualization seminar we had quite an energetic discussion about this video, however.  There seemed to be a lot of skepticism in the room about this visualization.  “It’s not art,” claimed the artists in the room, and the scientists (who were not biologists) were suspicious of its scientific content.  I’m here thinking this is the greatest thing since sliced bread, and they’re tearing it apart.  What gives?  Are we distrustful of something that looks slick and expensive, as opposed to something homegrown?  I haven’t seen such resistance to people’s aesthetic garage experiments.  Perhaps because the garage experiments are simply celebrating aesthetics, not trying to convey scientific content.

One aspect of this video, of course, is its emotional content, which can serve to motivate people to learn biology.  It uses different camera angles, an movement, and music, to make the viewer feel that they are zooming around these dynamic views of the inside of the cell.  In terms of how people learn information cognitively, this is also useful. Multiple representations of a phenomenon are very useful in helping people make sense of information.  Most science content is presented quite abstractly.  As our guest speaker Martin Kemp said, this isn’t the science lesson, it’s the teaser.

Certainly, this video doesn’t stand on its own — it needs verbal support.  Presumably an instructor would use it before or after instruction where the content is more explicitly explained.

There is an emotional narrative here, said the seminar participants.  How does that relate to the intellectual narrative.  Does this compromise the science?  One claimed that there is incredible intentionality depicted here.  The processes we see aren’t random, it’s very cooperative, like a small city.  These little things are working very hard to accomplish what they do.  They’re not self-conscious, but still are active agents.

This is dangerous, several people argued.  We don’t know if these objects have intentionality.  It turns out that the Discovery Institute co-opted part of this video to illustrate that God exists in the cell.

But, I argued against this.  The “intentionality” that people saw in this video, I think, was their own anthropomorphizing.  There was no intentionality inherent in the video — only motion.  Any intentionality is just a metaphor, just like the “selfish gene” is just a metaphor. It can help us to imagine these ideas by ascribing intentionality, perhaps, but we need to be very aware that it is just a metaphor.

So, I think that this video is great — it helps us imagine something we can’t usually see and relate to scientific content in a new way.  Phooey on the naysayers.  Does anyone agree with me?

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Since I’m woefully behind in posting on my own blog, I’m grateful to Sarah over at a Schooner of Science who wrote up an interesting article on the Chemistry of Kissing.  I was meaning to write something on this topic for a while, actually, since there was an interesting symposium at the AAAS Meeting in February on the Science of Kissing.  They covered several aspects, including the “genetic sampling” theory described by Sarah, below.  Another researcher at that conference did fMRI scans on people who were in love.  You can hear the Science podcast on that interview here. And a detailed report of the AAAS symposium with all sorts of juicy theories about why we like to smack lips here.

Read more of Sarah’s (aka Captain Skellett’s) posts on her main blog at A Schooner of Science.

Here’s her post:

In the words of Henry Finck, “is not a kiss the very autograph of love?” Well, some kisses are better than others Frinck, and it can be hard to tell who’s gonna be good and who’s not. The one who seems perfect on paper can be absolutely shocking in the lips department, while the bad-for-you going-nowhere person can make you weak at the knees after a mere second of lip action. Why the difference?

If you think about it in terms of biological selection, a kiss is a pretty important thing. I consider it a selection factor, cos sure as hell wouldn’t stay with someone who was a crap kisser, and I bet you wouldn’t either. Now, within my friendship group there’s been quite a bit of cross-dating (or whatever the term is) over the years, and I can tell you that the people I think kiss great do not always get the same ruling from my friends. Some couples have chemistry, and some just don’t.

WHY? What are we tasting on their lips? What in a kiss is so important that it is given a make-or-break status in choosing a mate?

The best theory around is that a kiss gives you information (though taste and smell) about the other persons immune system on a genetic level, in particular the MHC complex. Let me tell you the story.

In the dark and murky depths of chromosome six lies a section of some four million nucleotides, genetic material that encode for MHC’s – major histocompatibility complexes. Histocompatibility being a historical term, as it was first identified as determining which blood type you have – A, B, AB or O. The section of DNA on chromosome six encodes for a whole bunch of different MHC molecules, and the alleles are codominantly expressed – meaning you make both the maternal and paternal products.

Behold MHC molecules, there be the peptide binding cleft and there the transmembrane region that acts like an anchor, yarr!

MHC Class 1 molecules are expressed constitutively in all nucleated cells, while Class 2 molecules are expressed only in special antigen-presenting cells of the immune system, like dendritic cell, macrophages and B cells. There’s also Class 3 products that are secreted instead of membrane-bound, but enough blah-blah, on with the story!

Your body can be a bad neighborhood, so police natural killer cells and other members of the immune system drive by frequently to check the ID of your cells, to see if they are terrorists infected or cancerous. If an MHC protein is visible and is only expressing self-proteins, the cell can live another day.

Now let’s say a cell gets infected by a virus, which pokes in some genes of its own so it can hijack our replicative machinery, much like a pirate commandeers a ship to make booty.

Virus oh noes ensue.

Caught red-handed holding non-self proteins, the cell is told to kill itself quietly (apoptosis), or is ruthlessly killed by the immune system in a dramatic action sequence worthy of Schwarzenegger.

Of course, it’s a little more complicated than this. Instead of just two MHC’s on your surface, you have heaps (it took too long to draw!) The MHC region of the genome is extremely polymorphic, and the goal is to have as many different versions of MHC possible, both in your own DNA and across the species. The more variety there is, the more likely someone out there will have what they need to survive HIV or H1N1 or any of the other freaky viruses that get us worried now and then.

So what would happen if your parents ignored the signs given to them by the almighty kiss, and you don’t have much variety in your MHC’s.

The virus slips past the immune system like a ninja, will replicate and spread, and you’ll get sicklier.

So when we kiss someone, we’re really just saying “Hey, how’s your MHC compared to mine? Ooh… you taste different… MAN our kids will have kick-ass immune systems!” Opposites certainly attract in this case.

How did they discover this? They got men to work out, and then asked women to smell their sweaty shirts and pick which one smelled better, and then they ran genetic tests. Women were more likely to dig the stink of a guy whose MHC was very different to her own.

It’s interesting to note that women on the pill are more likely to choose the WRONG PERSON in these tests, possibly because their body thinks it’s pregnant and it’s a bit late to go choosing a mate based on genetics. This could be a contributing factor to divorce – people hook up when the woman is on the pill, they get married, she stops taking it to become pregnant, and suddenly they lose their chemistry. Something to keep in mind.

So go out there and kiss! Sample the MHC molecules around you, and run your own genetic screening! Albert Einstein himself said “any man who can drive safely while kissing a pretty girl is simply not giving the kiss the attention it deserves.”

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From AP via National Geographic - click for original

Well, I bet they’re all that cute.
But I don’t care how big and manly you are, you know you’re moved to scritch it behind the ears and say “who’s a cute little kitty? That’s right, you’re a cute little kitty. Waschawhaschawhuh.”

From the original article at National Geographic.

June 29, 2009—The discovery of ten lynx kittens—including the young cat in this May 2009 picture—this spring marks the first time newborn lynx have been documented in Colorado since 2006, heartening biologists overseeing restoration of the mountain feline (lynx facts, map, and more).

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I came across a new science blog recently – A Schooner of Science — and really enjoyed Sarah’s fresh and funny writing style about all sorts of things that this blog doesn’t tend to cover — namely, biology and chemistry.  (I write about them when I can, but, well, it does all come down to physics, after all, right?  Right?).

Sarah cheerfully agreed to cross-post one of her recent articles in lemmings (yay lemmings!) and whether it’s really true that lemmings throw themselves off cliffs to reduce their population.  Enjoy, and check out a Schooner for more stuff (most recent posts — 5 most remarkable animal penises!).

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Nothing like going retro and playing a game or fifty of LEMMINGS!!! I squandered many an evening in my youth curled over a computer screen, thinking of ways to keep those suicidal wanderers alive while they walked carelessly towards cliffs.

Some of the levels were so bizzarro I’d wonder “how did they get themselves INTO this mess? Do they WANT to die? Cute little green-haired munchkins!” For fun, here’s a real lemming – still cute but in a more hamsterish way:

At some point I was introduced to the idea that yes, lemmings DID want to die because of a brilliant population-control technique ingrained in their DNA. I’ve had many a teacher who have lamented the human desire to be fruitful and mulitply, crying that we were destroying the planet out of sheer numbers. Whether we would continue to survive would depend on whether we realised that space was running out and slowed down… otherwise we’d bang ourselves straight into extinction. Are we an r-selected species, or a K-selected species, is our growth rate exponential, or are we just midway up an S-curve? Whenever I read that the suicide rate was increasing, I would think to myself – maybe we ARE like the lemmings. Maybe this is all some genetic grand-scheme to thin out our numbers.
I don’t think that anymore, doesn’t it sound a bit ridiculous that you can have so many animals around that they disappear? It sounds a bit like Jimbo Kern from Southpark – “We’ve got to kill more animals so they won’t die!”
And the lemming thing – it’s all a LIE!!! Those lemmings didn’t kill themselves. The poor little rodents were chased off a cliff for a Disney movie. This Disney movie in fact, White Wilderness.

Hell, these lemmings weren’t even migrating and accidentally fell into the sea, or thought there was something worth swimming to on the other side of the ocean. Nope, they were pushed off the edge by film makers just to get the right shot. Lemmings aren’t even native to Alberta, Canada, where the footage was taken – they bought them from Inuit kids! So consider this myth debunked. It wouldn’t be the last time television pushed animals into killing themselves either – consider Happy Tree Friends.

If you want to play the game again and relive the lemmings good times, do it here Love the hair.

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Originally posted on a Schooner of Science here.  See more of the Captain’s scientific musings over on her Schooner.

I am a science education and communications consultant -- view my website for my full range of services.

My friend and fellow science writer Jen Frazer has started a new blog (well, two actually, but let’s start with the first). I don’t know how she can spend a whole day at work writing copy, and then come home and spin out gorgeous and witty prose, but, hey, she didn’t win the AAAS Science Journalism Award for nothing!  In the Artful Amoeba she explores charismatic microfauna, or the “weird wonderfulness of life on Earth.”  By way of explanation, she says:

I say: it’s not the taxonomy that’s important. It’s the learning about the diversity of life on Earth. We don’t have to go to Mars to find living wonders, and though I respect those that want to, I wish the 100% real living organisms on Earth could get half the attention the putative creatures on a planet millions of miles away do. The curiosity cabinet is long gone, but the curiosities are still here, just waiting for us. All 10,000 ferns. All 70,000 known fungi. All untold millions of species on Earth. I want to show you. I’m passionate about this stuff, and I like to make it fun. Please join me.

Go on.  Check it out. You know you want to.

Her other blog is Home Cooking Well - A blog about how your kitchen can enrich your life, your wallet, and your sense of humor.
As a teaser, here’s one of her recent posts on Moss That Swings Both (all?) Ways

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I’m sometimes greatly amused by the quality of press release science writing that is taking the place of professional science writing these days, since no one will pay for us to do it full time anymore (Science Daily, a major source of internet science news, is made almost entirely of press releases reprinted verbatim. And you’ll notice that this very blog is, so far, gratis).

For instance, a press release on one of the coolest things I’ve seen in a long time includes this sentence, seemingly lifted from Timmy’s 3rd grade report on mosses:

At first glance, mosses and human beings have little in common.

Gee, ya think? I’m imagining myself at a coffee shop holding a cup of steaming tea and sitting across the table from a noticeably uncomfortable bryophyte.

Cough.  *blink*

Me: So, read anything interesting lately?

Moss: No.

See? Not much in common. Strangely, this doesn’t differ greatly from most of my actual dates.

I don’t want to seem too hard on the author here, since 1. the release was probably first written in German, and 2. this is actually one of the clearer and more helpful press releases I’ve read. In any case . . .

Scientists from ETH Zurich and the University of Freiburg im Breisgau report that they were able to insert DNA from humans and bacteria into the moss Physcomitrella patens (sounds suspiciously close to “patent”) and the moss was able to manufacture human proteins without any further help. Yes, they basically cut and paste. And the moss said: OK! Cool!

For those of you unfamiliar with the Way of the Cell, DNA makes RNA (with the help of proteins called RNA polymerases), and RNA makes proteins (with the help of cell organelles called ribosomes). The reason this moss-cular feat is astounding is that doing the same thing with flowering plants will get you nada. The mammalian gene start and end sequences have evolved themselves right out of business when placed in a similarly much-modified flowering plant. Not that there’s much of a reason that that would *ever* happen in nature. Now in an evil mad plant scientist laboratory, on the other hand . . . Belgians + petunias = Brussels sprouts. Mwa ha ha ha ha ha . . . . .

How is it mosses can do what so-called “higher” plants cannot? It’s a mistake to think of mosses as “primitive” in the sense of “inferior”. Both mosses and flowering plants have ancestors that were alive at the same time. What mosses are is “less-derived”, in biologist-speak. The lineage that gave us mosses just didn’t change as much over time as the lineage that produced flowering plants, because they found they were well-adapted as-is to their particular niche (forests, rocks, sidewalk cracks, and the sets of “Lord of the Rings” adaptations). Like sharks, they found a sweet gig and they stuck with it.

According to Ralf Reski, botanist and co-author of the paper announcing this discovery, as part of this cozying into a niche relatively early on for multicellular life (moss seem to have sprouted out of the ocean and then pretty much called it a day) mosses have stayed genetic generalists. And this easy-going gene-set enables them to translate a wide range of DNA. In fact, hold on to your hats . . .

This cross-kingdom conservation of mammalian and moss protein production machineries is phylogenetically profound, and has several implications for basic and applied research. Comparative genomics, as well as functional studies, have recently established major differences in metabolic pathways and gene function between flowering plants and P. patens, and have suggested that a substantial moss gene pool is more closely related to mammals than to flowering plants (Frank et al., 2007; Rensing et al., 2008).

–Plant Biotechnology Journal, Volume 7, Issue 1, 2009. Pages: 73–86

Dude! An article in the Plant Biotechnology Journal just blew my mind!

Who knew? Well, maybe John Wyndham.

In the next post, we’ll take a look at what on Earth possessed these scientists to stuff human genes into a soft, green, cushiony object and at why biology is WAY cooler than nuclear physics. Stay tuned.

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Read more on Jen’s blog here.

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In these tough economic times, waste not, want not, right?

So, an enterprising Explainer at the Exploratorium thought well, there must be some good use for all these cow eyes we dissect on the museum floor every day.

So, yup, you guessed it.  Kudos to those crazy kids for the following recipe:

Tacos de Ojo (Eye-ball Tacos)

Makes 1 heaping taco

2 Cow Eyes (muscle and fat trimmed off)

1 tablespoon Olive Oil

2 teaspoon Salt

2 teaspoon Pepper

1 Lime

1 Corn Tortilla

Tapatio Hot Sauce

Read more over  (including the taste test) at the post on their blog.

Though you might not want to do this in your classroom… might get a few parents a tad upset.

Image from London Matt on Flickr.

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Ren West

Here’s a problem most of us never have.  How do you raise tadpoles in the classroom without killing them off?  Which species are best?  And then what about the resulting frogs?  A teacher recently raised this on the Exploratorium teacher email list, and perhaps others can benefit from these words of accumulated wisdom.

First, you gotta get the egg sacs.  These teachers were in the bay area, and recommended the vernal ponds near Merrit College in Oakland.  It’s smart to make sure you’re in an area where collecting is allowed, and try to find out what you’re collecting in advance (and not, as one teacher recounted, an endangered species).  One veteran teacher (who seems to know the answers to everything from physics to, well, tadpoles) says he uses spring water, mixed with a couple gallons of the water taken from the pond where he got the sacs.   He also picks up some stray twigs and rocks that have growth on them, assuming they carry some of the tadpoles native food stuff.  One teacher quoted a book (below) which remarked that you should have no more than 5 eggs per quart, between 62 and 72 F. What he ends up with are California tree frogs (small, noisy, and pretty).  He used to feed them small crickets, until he found one of the crickets eating the tadpoles.  Now he uses frog food (from Pet Mart), though a recommended book (below) suggests feeding them goldfish food. That teacher keeps the tank clean, and keep some of the native water and debris in the tank when he dumps some of the dirty water and adds spring water to replace it.

He adds:

They can climb anything, and are small enough to get out of tiny cracks. Your aquarium should have a good seal on the netting. They are also very smart so I usually put an open copy of Wind in the Willows by the tank for them to read (they move their little lips when they read) when kids aren’t around.

The NSTA produces a book called Classroom Creature Culture: Algae to Anoles
with 3 articles on frogs.    She also suggested Creepy Crawlies and the Scientific Method: More Than 100 Hands-On Science Experiments for Children which has a section on frogs.

For those of you erstwhile teachers trying to become hydra ranchers, one teacher reported success using pond water and feeding them daphnia or copapods, adding pond water every week, and keeping the tank in a window without direct sun.  Feeding them brine shrimp didn’t work for one teacher.

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Our latest Beyond Penguins and Polar Bears podcast from the NSDL is up!

What’s For Dinner? Teaching Arctic Food Chains

We already know why polar bears don’t eat penguins, but what do they eat? In this episode, we’ll share a simple activity that opens a window to understanding a unique ecosystem as one example of a food chain – the Arctic Ocean. For more information on ecosystems and food chains, see Issue 13 – Tundra: Life in the Polar Extremes.

Photo by Ansgar Walk

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