In one of my undergraduate chemistry lab courses the teaching assistants ran a “Break List”. Every time you broke a piece of glassware, you got a score, depending on how expensive that piece of glassware was. Test tubes were only a few points, but breaking the rotavap would instantly get you to the top of the list. At the end of the course, the person with the most breakage points would have to bring cake.
I didn’t break very much, but things did break quite regularly in the lab, and it wasn’t just inexperienced students breaking things. This new Lego scientists video was inspired by many fallen flasks, beakers, and test tubes.
What’s on the board?
The lab in the video appears to be a molecular biology lab, because the letters that the postdoc writes on the board at the start represent the EcoRI restriction site. This is a little sequence of DNA that is recognized by an enzyme called EcoRI. Whenever EcoRI finds “GAATTC” in the DNA, it will cut that DNA strand right after the G.
GAATTC is a palindrome sequence: The bottom, complementary, strand is the reverse of the top sequence. In DNA, each G pairs with a C, and each T pairs with an A. So the strand opposite GAATTC says CTTAAG. Opposite strands also run in opposite directions, so if you read the top one from left to right, the bottom one goes from right to left. That means EcoRI sees the “GAATTC” sequence also at the bottom (read from right to left) and cuts both ends of the strand. The cut appears after the G on both ends.
EcoRI helps molecular biologists because it means that they now have a tool to cut DNA at a very specific point. They can cut out a piece of smaller DNA from a longer strand, by cutting at the GAATTC sites. There are many restriction enzymes that each recognize a very specific sequence, so there are a lot of possibilities for cutting sites! It’s a tool used for many different applications in molecular biology labs.