How penicillin works

Posted on March 18, 2011 by Michael

I’m currently in the midst of a short break I’m taking whilst studying for a massive microbio test I have in a few hours. And what better way to take a break than to post about one of the essay questions I know will be on the exam?

β-lactam antibiotics include penicillin and cephalosporins. (Everything that follows applies to both, but most people seem to be more interested if the topic is the more familiar penicillin subgroup.) The way these antibiotic works is by attacking the cell walls of bacteria. This makes gram-positive bacteria more susceptible than gram-negative bacteria; gram-positive bacteria have an outer peptidoglycan layer whereas gram-negative bacteria have their peptidoglycan layer between a plasma-membrane layer and an LPS layer. (No, I’m not going to define all these terms I’m using.)

Transpeptidase molecules are necessary for catalyzing cross-linking of glycan-linked peptide chains. Penicillin, all coy and sneaky, causes transpeptidase to link to it (penicillin) instead. (Transpeptidases are known as penicillin-binding proteins, or PBPs. I find the name misleading since it sounds like their purpose is to get all buddy-buddy with penicillin.) This prevents cross-linking. As I’m sure every nerd knows, cross-linking is what gives the peptidoglycan outer wall much of its strength. So while cell wall synthesis continues unabated, no cross-linking is happening, thus weakening structural integrity. Mike Holmes would be pissed if he was a biologist and he saw this happening. (Come on, HGTV fans, I know you’re out there.) Furthermore, autolysins are being released. What this means is the gram-positive bacteria has a weak and self-degrading outer wall. Osmotic pressure eventually causes lysis.

Now please excuse me while I enter hour 6 of studying for the (literally) 109 other things I need to know for my upcoming test.

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Art in science

Posted on September 4, 2009 by Michael

Thanks to Carl Zimmer for posting a link on his Facebook page to this.

An artist by the name Luke Jerram has a website/project devoted to glass sculptures based on microbiology. The most beautiful one for me is the HIV sculpture. It’s frighteningly disconcerting to see, and I think that’s some of its appeal.

Viruses-Lukejerram

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How inviting

Posted on March 23, 2009 by Michael

I have been cordially invited to attend a viewing of Expelled at the University of Maine at Augusta campus on Tuesday, April 7 at 5:30 p.m. until 8:00 p.m. (You must be logged into Facebook to view.) Here is the event description.

We will be watching “Expelled: No Intelligence Allowed”

The debate over evolution is confusing and to some, bewildering: “Wasn’t this all settled years ago?” The answer to that question is equally troubling: “Yes…and no.”

The truth is that a staggering amount of new scientific evidence has emerged since Darwin’s 150-year-old theory of life’s origins. Darwin had no concept of DNA, microbiology, The Big Bang, Einstein’s Theory of Relativity or of the human genome.

Then after we will be hanging out and discussing it

For more information on this move check out http://www.expelledthemovie.com/aboutthemovie.php

Amazing. First, they still think evolution is up for debate. Creationist ignorance check point one. Next, they call it a theory of “life’s origins”. How does evolution imply that at all? Creationist ignorance check point two. Then, of course, we get unrelated theories in physics. That’s three. And they could have hit so many more. Where’s the second law of thermodynamics? The ‘natural selection if a tautology’ bs? Come on! Amateurs!

I’m rather undecided about attending this. I am certainly not going to see the movie. I saw it once and that was torture enough, but I will be on campus around the time they will be having their discussion (and by this I mean ‘spreading of disinformation’). Perhaps I can lend my voice to be sure they don’t think this somehow supports intelligent design. Yes, that’s right. The person with whom I originally saw the movie (a young creationist minister) said he “loved that there was a lot of great science”. Of course, there is no science behind intelligent design, but the movie doesn’t even make an attempt to discuss science. It’s wholly about how there’s a big, mean conspiracy to keep intelligent design advocates down and out because “Big Science” is so evil. Oh, and evolution caused the holocaust. Can’t forget that gem.

I’ll keep you updated.

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