
Course: Molecular Biology – Part 2: Transcription and Transposition
Length: 7 weeks, 4-7 hrs/wk
School/platform: MIT/edX
Instructor: Stephen Bell, Tania Baker
Quote:
In Part 2 of this Molecular Biology course, you’ll explore transcription of DNA to RNA, a key part of the central dogma of biology and the first step of gene expression.
Take a behind-the-scenes look at modern molecular genetics, from the classic experimental events that identified the proteins and elements involved in transcription and transposition to cutting-edge assays that apply the power of genome sequencing. We’ve designed the problems in this course to build your experimental design and data analysis skills.
Yes, I’m about to rave about another MIT bio course. What can I say about this second course in the Molecular Biology trilogy that I haven’t said before about MIT’s bio-offerings: the in-class lectures are clear and engaging, they use animations and diagrams better than I’ve seen anywhere else, and the quizzes are based on interesting and occasionally amusing laboratory narratives (continuing the saga of poor confused Brian). And now that we’re all becoming experts on mRNA and DNA and PCR thanks to COVID, they’re more practical than ever.
I’d started this course back in 2017, right after I’d finished the first part on DNA replication. I could tell right away I wasn’t up to it – assays in particular were still too unfamiliar – so I dropped it almost immediately and went on to other things. I decided to re-take the first part late last year as prep, which helped. Things went a lot more smoothly this time around.
In basic biology courses, we learn that RNA is made from DNA. Here, we find out that it’s not a simple process. First, different cells make different proteins, so the same DNA has to make one set of proteins when it’s in a liver cell, and another set when it’s in a bone cell. And sometimes it has to make more utility proteins (like for digesting sugar) than other times. This is what epigenetics is for: how DNA expresses different RNAs, ultimately different proteins, depending on the circumstances. We got into nucleosomes in a big way, as well as promoters, suppressors, and activators that regulate transcription.
Then there’s transposition, which is kind of a secret you don’t hear about in basic biology. It’s a process by which pieces of DNA get pasted into genes just for the fun of it. Or to silence a gene. Or to create new mutations which may or may not be beneficial. Some downright scary statistics show up, such as: half the human genome is transposon-related sequences. But it’s ok, because most of them are ancient, more like fossils of transposons. And it could be worse: 80% of corn’s genome is transposon-related.
After all this, they snuck in an extra week on CRISPR, which was fun. That required a refresher of meiosis and crossover recombination.
And of course all of these were discovered by lab assays, and are still examined by those assays. How can you tell where the promoter is? How can you tell if a drug silences a destructive gene? How did we learn how RNA is released when transcription is done? Assays. Dozens of them. Keeping them straight is still my Achilles’ heel: which are in vivo, which are in vitro, which are quantitative, which yield sequence information, which are quick and easy, and which take months and cost a fortune?
Once again, while the post-video “test yourself” questions cover the specifics of a lecture, the graded quizzes are based on little lab scenarios: you’re trying to figure out how a particular organism regulates transcription, what assays do you need, what does this output show, what is your positive and negative control, what do you expect to see when you do this or that (and why would you really not want to do that in the first place). All this is in service of understanding exactly what’s happening in a process. As I’ve said before, you can’t fake your way through this.
The first three quizzes are included in the audit course so can be accessed for free. The final four quizzes can be unlocked for $99. This series is the first time I’ve paid for a mooc. I consider them worth it. You can decide for yourself after the first three weeks if it’s worth it to you.
There’s one more part to this molecular biology series: RNA translation into protein. I want to focus on reading for a little while, so I may take it later this summer, or I may wait until next year, but I’ll get there.