Did you know small fragments of DNA are circulating in your blood stream?
These short pieces of DNA are left behind after cells self-destruct. This self-destruction, or apoptosis, is a normal process. In the case of fetal development, certain cells in our hands die, leaving behind individual fingers. Immune system cells leave traces of DNA behind after they’ve tackled invading microbes. DNA can also appear in the blood when people have cancer.
I had the good fortune, last Monday, to hear Matthew Snyder describe this cell-free DNA in a fascinating talk and learn why DNA in the blood can be a ... Read more
"By night all cats are gray" - Miguel Cervantes in Don Quixote
I've always liked Siamese cats. Students do, too. "Why Siamese cats wear masks" is always a favorite story in genetics class. So, when I opened my January copy of The Science Teacher, I was thrilled to see an article on Siamese cat colors and proteins AND molecular genetics (1). In the article, the authors (Todd and Kenyon) provide some background information on the enzymatic activity of tyrosinase and compare it to the catechol oxidase that ... Read more
Imagine a simple hike in a grassy part of South America. You hear a rattle and feel a quick stab of pain as fangs sink into your leg. Toxins in the snake venom travel through your blood vessels and penetrate your skin. If the snake is a South American rattlesnake, Crotalus terrific duressis, one of those toxins will be a phospholipase. Phospholipases attack cell and mitochondrial membranes destroying nerve and muscle function. Without quick treatment, a snakebite victim may be die or suffer permanent damage (1, 2).
The phospholipase from the South American rattlesnake is called ... Read more
When my parents were young, summer made cities a scary place for young families. My mother tells me children were often sent away from their homes to relatives in the country, if possible, and swimming pools were definitely off limits. The disease they feared, poliomyelitis, and the havoc it wrecked were the stuff of nightmares. Children could wake up with a headache and end up a few hours later, in an iron lung, struggling to breathe.
To have an effect, a molecule must bind to a receptor and trigger a signal. Studying a receptor's structure can give us insights about the way this triggering process works.
Capsaicin is a fascinating molecule that puts the "pep" into peppers. Curiously, the amount of capsaicin in a pepper is measured with a test devised in 1912 by Wilbur Scoville. Dried peppers are dissolved in alcohol, this liquid extract is diluted in water, and trained people determine the pepper's Scoville value by "tasting" the heat.
I really wonder how these people are recruited. I like hot ... Read more
Pull a spaghetti noodle out of a box of pasta and take a look. It's long and stiff. Try to bend it and it breaks. But fresh pasta is pliable. It can fold just like cooked noodles.
When students first look at an amino acid sequence, a long string of confusing letters, they often think those letters are part of a chain like an uncooked spaghetti noodle. Stiff and unbending, with one end far from the other.
Molecular modeling apps let us demonstrate that proteins are a bit more like fresh pasta.
If we apply rainbow colors (Red Orange Yellow Blue Indigo Violet) to a protein chain, we can ... Read more
On pinene and inhibiting enzymes. People of a certain age may remember a series of really funny commercials featuring Euell Gibbons and his famous question about whether you've ever eaten a pine tree. "Some parts are edible" said Euell. Perhaps some parts are, but other pine tree products aren't so nourishing. Crystallography365, aka @Crystal_in_city had a couple of fun blog posts about pinene, ... Read more
In my last post, I wrote about insulin and interesting features of the insulin structure. Some of the things I learned were really surprising. For example, I was surprised to learn how similar pig and human insulin are. I hadn't considered this before, but this made me wonder about the human insulin we used to give to one of our cats. How do cat and human insulin compare?
It turns out, that all ... Read more