I failed as a teacher

Yesterday I visited my local evil government house of mail (a.k.a., the post office).  While waiting in line, I overheard a young boy behind me asking his mom, “But I don’t understand how DNA works.  I don’t get it.”  I glanced back and smiled at him and his mom, impressed that a boy that looked so young would know anything about DNA.  His mother explained patiently that she didn’t know and advised him to ask a science teacher. 

Cue the superhero music!  Science teacher to the rescuuuuue! 

I boldly turned around again with my brightest smile, proclaiming, “I’m a science teacher!” 

The boy, not impressed, asked, “Are you a scientist or a science teacher?”  (At this point I’m sure someone with acute vision could see my ego deflate just a bit.)

“I’m a science teacher.  Is that ok?”

“Well, I guess.  My science teacher really loves science.  She has all sorts of weird stuff in her room.  Like, she loves science.”

“Oh, that’s cool.  How old are you?”

“Nine.”

“Go ahead,” said Mom.  “Ask her your question.”

At this point I was prepared to explain that our bodies are made of lots of teeny tiny cells, and inside each one is a chemical called DNA that tells the cell what to do.  Instead, the question I got was much more specific. “Ok, how does the DNA say if you’re a boy or a girl?  I don’t get it!”

Instantly, since I teach high schoolers, images of sperm cells, egg cells, chromosomes, and so on go tumbling through my mind, and all I can think of is sexual reproduction.  My jaw drops a little bit. 

“Um,” I stutter to Mom, “I’m not sure how to explain that to a 9 year old.”

Life As We Know It…well, almost

La Jolla, California…one of my favorite places on the planet…and now in the science headlines.

Researchers at the Scripps Institute have synthesized RNA enzymes that can replicate themselves.  But that’s not all.  The RNA enzymes also appeared to “breed” and even “evolve”.

Interesting stuff!  Read more about it in the news here.

Do-it-yourself genetic engineering

There’s an interesting article in the news today about amateurs attempting their own genetic engineering at home.  A quick excerpt from the article:

In her San Francisco dining room lab, for example, 31-year-old computer programmer Meredith L. Patterson is trying to develop genetically altered yogurt bacteria that will glow green to signal the presence of melamine, the chemical that turned Chinese-made baby formula and pet food deadly…

…But critics of the movement worry that these amateurs could one day unleash an environmental or medical disaster. Defenders say the future Bill Gates of biotech could be developing a cure for cancer in the garage.

You can read the rest of the article here.

Merry Christmas!

The Night Before Christmas–cell style!

The Night before Christmas in a Cell

(found at the AP Bio list-serv)

Twas the night before Christmas and all through the cell,

Not a creature was stirring, not even an organelle.

The chromosomes were hung in nucleus with care,

In hopes that mitosis would soon take place there.

The genes were all nestled and snug in their beds,

While cells in their pj’s and vacuoles of sap,

Had just settled down for their Interphase nap.

Then in the nucleus there arose such a clatter,

The chromosomes sprang from their beds to see what was the matter.

They flew from the nucleoplasm in less than a flash,

Hit the nucleolus and made quite a crash.

 

The light on the center of the newly formed cell

Gave the excitement of metaphase to the objects beheld.

Then what to the scientist’s eye should appear,

But a division – how odd!- with a haploid now here.

With a nod, he said, “This is strange for mitosis.”

Then he knew in a moment it must be meiosis.

More rapid than eagles his excitement came,

And he whistled and shouted and called them by name:

Now eggs! Now sperms! Now X’s and Y’s!

On, diploids! On, haploids! On, Gametes and XY’s!

To the top of the cell! To the top of the ball!

Now dashaway! dashaway! dashaway all.

 

Now into the middle the chromosomes flew,

With a sleigh full of Genes and DNA too.

And then in a twinkling they precisely did start,

The duplicating and changing of each little part.

As the scientist moved his head and was turning around,

Suddenly meiosis came with a bound.

They were all double up from their head to their feet

And spread through the cell in one great sheet.

And their outside were all mingled with bluish and green;

A bundle of colors was all that was seen.

The strands how they twinkled, Their movements how merry!

The reds were like roses and red as a cherry!

The small bits of black were like that of a crow,

And the white on the ends was as white as the snow.

 

The strands, still held by the centromere,

Were through crossing-over, but still very near;

Each part looked to him like a little round belly,

That would shake, if it could, like a bowl full of jelly.

They were chubby and plump, a right set of each,

And he sighed when he saw them, for none he could reach.

A quick divide and untwist of a strand

Soon let him know he’d seen nothing so grand.

 

They stopped once again, but went straight to work,

And filled all the new cells, then turned with a jerk,

And laying the membrane ‘round the nuclear glob,

And giving a nod, they finished their job.

They sprang to their sides, their teams gave a whistle,

And away they all flew like the down of a thistle.

But he heard them exclaim as they went out of sight,

“Happy Christmas to all, and to all a good night!”

Ultraconserved regions of DNA–we still have a lot to learn

In the news two days ago on Yahoo I read the following article: Mysterious DNA Found to Survive Eons of Evolution.  Basically, scientists have discovered segments of DNA that have survived long periods of evolution though they seem to have no apparent purpose.  The sequences in question are not non-coding or “junk” DNA. 

Since these segments haven’t been lost as a result of natural selection, one would assume they give some important advantage.  However, mice were bred to lack these sections of DNA, and they appeared to be healthy.

The article goes on to discuss potential answers to the puzzle, such as the possibility that these strands code for multiple layers of information or that they might protect against diseases that only rarely strike. 

What leaves me in awe is the fact that despite learning so much over the past few hundred years–and especially the past 60 or so–we still have so much yet to learn!  This article goes to show that science is certainly not stagnant.  Science doesn’t have all the answers about how the natural world works…though it’s still working on it!  🙂

Evolution of pregnancy in mammals

Summary: Research suggesting that a change in transcription factors may play an active role in the evolution of structures like the uterus (specifically, the HoxA-11 transcription factor, which is present in all placental mammals but not marsupials).

Interesting stuff. Go here to read more.