Archive for April 2013

Triple Feature

Have I mentioned lately how awesome chemistry is? It’s pretty freaking awesome. I’ve learned several things this week that absolutely blew my mind, so, naturally, I’m going to share them with you (yay, sharing!).

The first thing has to do with Scotch tape. I don’t usually jump up and down with excitement over my chemistry textbook, but this week’s chapter on spectroscopy and light contained some information that was jump-worthy (to my roommate’s surprise). Apparently, if you peel a roll of Scotch tape in a 1.3µbar vacuum (that’s an enclosed space with very, very low pressure), it actually emits x-rays strong enough to create the image of a finger bone on dental film in a mere second. Electrons sometimes suddenly accelerate as the adhesive strip is separated from its backing creating a visible stream of blue light (1). It only occurs in a vacuum, probably because moisture in the air acts as a short circuit to the movement of electrons in the tape. In addition, different brands of tape give off different spectrums of light. There are all kinds of potential applications for this strange phenomenon from electron-bursts directed at cancer cells to research in nuclear fusion (2). My roommate and I peeled some tape in the dark in our dorm room and freaked out about observed the same glow-in-the-dark-esque light emission that was observed by scientists in 1939. Pretty incredible, if you ask me.

The second thing has to do with apples. Again with the apples, I know. But this doesn’t have anything to do with cider. In the April 8, 2013 edition of Chemical and Engineering News in the Government and Policy section (31-33), there’s an article (“Engineered Apples Near Approval”) about genetically engineered apples that don’t brown. There’s a good chance that these apples will be approved for use in the U.S. because there’s really no reason not to grow them except for a few concerns about very unlikely cross-pollination with other apple trees. The Arctic Granny Smith apples that are being modified by Okanagan Specialty Fruits of British Columbia have simply had a gene inserted that is a duplicate of a gene apples already contain (the one that causes a chemical reaction that results in browning). The duplication causes cells to undergo a natural process that prevents double-genes from appearing. This technique is known as co-suppression, and the gene insertion is performed using a modified bacterium. There are a lot of good reasons to make these apples. Money will be saved for growers, packers, and retailers who won’t have to worry about brown spots on bruised apples. In addition, the consumer will throw away less fruit. The modified Arctic Granny Smith performed just as well as other apples against pests and diseases, so the concerns about proliferating orchards with a more susceptible variety were eradicated. The nutritional value of the apple also improves because the chemical largely responsible for browning, an enzyme called polyphenol oxidase (PPO), breaks down the antioxidants in the apple’s flesh when exposed to air. Without that enzyme, more antioxidants remain intact for consumption. I’m not totally pro-GMO or anything because some of them (like Monsanto’s NewLeaf potatoes that produce their own pesticides) are kind of unnerving from an environmental stand point. I think that making apples that don’t brown is a good use of our understanding of genes. Plus, it’s pretty nifty.

File:Rheobatrachus silus.jpg

A Gastric-Brooding Frog

Finally, the article right after the one about apples (“Reviving the Dead,” 34) summarizes a TED-talk about de-extinction. With our ever-increasing understanding of genomes, it’s apparently now possible to bring extinct species back into existence. The article says, “The talks were not about mere possibilities. Recent advances in cloning, genetic engineering, stem cell research, and other scientific fields have brought humans much closer to [bringing extinct animals back]. One of the biggest announcements at the conference was the successful creation of a gastric-brooding frog embryo. The frog has been extinct since 1983.” So, basically, now we have to decide whether or not it’s ethical to bring extinct species back that might no longer have habitats. There’s a lot of debate over whether or not it would be right to re-create a species just to keep it locked up zoos or labs. Our bio-technology has advanced more quickly than we’ve been able to repair environments. Also very interesting.

That’s all for today’s post. I hope you find these tidbits as fascinating as I did. Keep reading! Subscribe! I’ll be updating monthly or so from now on : )

 

-Ashley

 

Sources:

(1) Harris, Daniel C. “18: Let There Be Light.” Quantitative Chemical Analysis. 8th ed. N.p.: n.p., n.d. 389. Print.

(2) http://www.nytimes.com/2008/10/28/science/28xray.html?_r=0

(3) Bettenhausen, Craig. “Engineered Apples Near Approval.” Chemical and Engineering News   (2013): 31-33. Print.

(4) Heidari, Nader. “Reviving the Dead.” Chemical and Engineering News (2013): 34. Print.

Every year at Sweet Briar College there’s an event called Briar Bowl in which a bunch of teams of nerds students with one faculty member each get together and compete by answering trivia. It’s loads of fun. There’s the opportunity for bragging rights hanging out with friends and faculty. I hope other schools host something similar. The questions are totally random: everything from pop-culture (author of 50 Shades of Gray) to mathematics (if an object is traveling at 5ft/s, how far has it gone in an hour?). The Dean reads the questions, and the students all scribble their answers in a mad flurry. When the science questions come up I get handed the pen whether I have a clue or not.

Once, I actually did know the answer. The particular factoid in question had been drilled into my head over and over ever since pre-biology in seventh grade. Question: What two scientists won the 1962 Nobel Prize for Physiology/Medicine for solving the conundrum of DNA’s structure? Answer: Francis Crick and James Watson (and technically, Maurice Wilkins).

Helix

Single Helix

Disclaimer: I’m not a biologist. Recently, I ended up learning a few things about DNA as a result of fellow Sweet Briar student, Samantha Meiser’s research. Before I get into that, I’d like to take a moment to recognize Rosalind Franklin, whose research on the structure of DNA was somewhat undermined by the official winners of the Nobel Prize. Rosalind Franklin took groundbreaking X-ray photographs of DNA molecules which revealed their helical (spiral) structure. Although Franklin had died by the time the award was given, it’s unlikely that her efforts would have been noted anyway, given the attitudes of those who received the prize. Francis Crick once admitted “I’m afraid we always used to adopt — let’s say, a patronizing attitude towards her” (1). That’s not to say that Crick, Watson, and Wilkins didn’t do valuable research. They did. But so did Franklin. Read this article for more of the story.

Anyway, some research has been done since the ’60’s which reveals that the double helix isn’t the only structure for DNA. What Watson and Crick did was connect the single helix’s from Franklin’s photographs, revealing that the actual structure is a double helix. Here’s a basic run down of this DNA (deoxyribonucleic acid) structure: the “double helix” is two long chains twisted around each other (like a swirling ladder). The chains are made of a few types of molecules, notably nucleotides. Nucleotides in DNA make up nucleic acids which fit together in neat pairs when the helices are fitted together. Below is a video for kids that actually explains it pretty well, and it’s only like two minutes long:

So, just to throw a curve ball at you, there are actually other structures of DNA, like the g-quadruplex (this is what Samantha researched). G-quadruplex DNA is square-shaped, and consists of four of the same nucleotides (four guanines). Recent research has shown that this form of DNA is likely to occur naturally in some cells, and studying it may be valuable in understanding how cancer grows and spreads (2). It is believed that g-quadruplex DNA is important in the process of DNA replication (definitely check that link out). Therefore, if something goes wrong with the g-quadruplex structure, there could be serious negative impacts on the production of healthy DNA molecules (3).

File:G-quadruplex.svg

G-Quadruplex Molecule Structure (NOT a double-helix)

I’ve been under the impression that the double helix is the only structure for DNA. One of the reasons I choose to study science is that it’s always changing and advancing. You never know what you might learn to be true or untrue. In organic chemistry, there were numerous occasions in which the best the textbook could do was to say “it is believed that….”

What I’m learning today might be proven totally wrong in the next few years, but that’s okay. Science has to be adaptable and open to new possibilities, possibilities that we haven’t even imagined yet.

Thanks for reading : )

-Ashley

 

(1) http://www.pbs.org/wgbh/aso/databank/entries/do53dn.html

(2) http://www.scientificamerican.com/article.cfm?id=four-strand-dna-structure-found-cells

(3) http://bioinformatics.oxfordjournals.org/content/25/12/i374.full