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A Picture Is Worth a Thousand Intermediates: How to Optimize Studying Biochemistry

Every pre-med student can agree: memorization is HARD and memorization is important. To vex us even more, some MCAT topics only require surface-level knowledge, while others seem to require an endless parade of facts. Take metabolism for instance; remembering that HEXoses have six carbons? Not too bad! Remembering that “py-ru-vate” has “1-2-3” carbons? Still…OK…but starting to stretch. Remembering that 3-phosphoglycerate is converted to 2-phosphoglycerate by phosphoglyceromutase in glycolysis, which occurs after the first ATP are produced, but two steps BEFORE formation of pyruvate? Wait…and how many carbons do those intermediates have, was it still three? Good grief.

Of course, glucose metabolism is one of the MCAT content pieces that requires the highest number of information “bullet points.” The most recent AAMC content PDF dictates that we learn all substrates, products, and net ATP production per glucose in glycolysis — and that’s without even touching on other metabolic pathways! Simply listing out “MCAT-required Glycolysis Facts” on paper could take up several pages of space, and could get intimidating, fast. But when was the last time you thought about memorizing something? And I mean actually thought about what your brain was DOING during the process of memorizing a tidbit of information that might be tested on an exam. Most of us don’t think about how, or why, a given memorization technique is working, and sometimes we just study content however our friends happen to be studying at the time.

And there are SO MANY ways to commit science content to memory: flashcards, study sheets, verbal mnemonics, applied practice problems, practice-teaching a lesson to a group of friends, even staring at a book while hoping and praying that the mishmash of letters and numbers on the page PLEASE burn themselves into my brain somehow (looking at you, OChem). These options all have their pros and cons, and some can be combined with one another. Really, though, only the applied methods are highly likely to create long-lasting, useful memories. The more we pre-test and re-test our knowledge of a subject — that is, the more we try to apply the knowledge that we may or may not have — the better our recall of that subject tends to be.

And this might be surprising given how often college classes seem to test information that amounts to stacks of flashcards, but our brains actually handle information better when it’s connected to other information. People naturally recall connections—like the shortest path to class, or the right sequence of buttons to perform their favorite video game combo—much better than how we handle huge lists of individual facts. While many techniques exist to take advantage of this quirk, one that naturally lends itself to the MCAT is called the method of loci. This method is, essentially, taking advantage of our brain’s spatial memory abilities by pretending that any information exists somewhere in a spatial arrangement. When this is pictured as a room, or a series of rooms, the method of loci is often referred to as a “memory palace.” This idea has been presented in pop culture by shows like Sherlock and The Mentalist to seem like a veritable magic power that Einstein-level geniuses use to remember anything and everything. But really, it’s not that hard for any learner to apply in most situations where extensive memorization is required, especially for sequences of connected information like (insert terrified gasps here) metabolic biochemistry pathways!

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One place you can find many more memory palaces like the ones in this article (over 250 and counting!) is in Sketchy’s MCAT videos. Blueprint and Sketchy even have a special bundle where you can get Blueprint’s full-length MCAT exams and Sketchy’s MCAT course at a discounted price.

One potential snag is that pyruvate is a tiny, submicroscopic molecule that I can’t ever actually see! But, one funny thing about human memory is that we can pretend essentially anything is whatever we want it to be, even if only for a few moments. Take a quick break right now, just pause for a few seconds with your eyes closed, and imagine there’s a piece of pie just sitting on a plate in the corner of the room. There (probably) isn’t actually pie there, but if you close your eyes you can likely imagine that there is. 

So, it would be easier for me to remember pyruvate as a macroscopic object — the more memorable the better, and I (obviously) love pie! Maybe I picture “py-ru-vate” as three pieces of RhUbarb Pie that are eleVATEd on a pedestal next to the desk in an imaginary room? Honestly, I barely know what rhubarb even is, but as long as I can picture three pieces of pie on a pedestal next to a desk, I can remember that each piece represents one of the carbons in pyruvate. And being able to connect those tasty pieces of pie to the other steps of glycolysis is where the method of loci really shines.

Since pyruvate is one of the end products of glycolysis, let’s take the final glycolytic step as a case study to see how the method of loci can make memorizing a complex process more manageable (maybe even fun and engaging) task. The final step of glycolysis is: an enzyme called pyruvate kinase (PK) converts the three-carbon molecule 2-phosphoenolpyruvate (PEP) into pyruvate, while also forming an adenosine triphosphate (ATP) molecule from adenosine diphosphate (ADP). I’m literally falling asleep typing that sentence. But I love pie! OK, focusing on the thing my brain has a natural affinity for: so I have my pyruvate pie elevated on a pedestal next to my desk, how can I remember that PK turns PEP into that pie? I used to play goalie in soccer/football, and any fans out there might be familiar with penalty kicks, which also happen to abbreviate to PK. And, of course, no penalty kick would be complete without cheering fans PEPped up about the high-stakes of glycolysis.

So now, on my desk, I can imagine, from left to right:

  1. A PEPped up crowd watching the penalty kick, representing PEP, the glycolysis intermediate;
  2. A soccer player taking a PK (kicking the ball toward my pyruvate pie) who represents the enzyme PK that turns the PEP into;
  3. The pyruvate pie itself, cut nicely into three slices to remind me that pyruvate is a three-carbon molecule;
  4. Anything else that I want to represent the ATP formed during this reaction, if I want to remember that as well. Since adenosine triphosphate pops up a lot in metabolism as an energy source, I likely want this to be something energy-related that I can picture along with a variety of situations. Like maybe three, fully-charged batteries on the plate next to my three pie slices.

After this, as long as I can remember a crowd cheering during a PK that’s kicked toward a dinner plate that holds some pie and batteries, then I’ve successfully tricked my brain into memorizing the final step of glycolysis in a surprising level of detail. As ridiculous as that little story is to read, I have other, even more fantastical mental pictures that helped me remember the details of every pathway I needed to learn for medical biochemistry (I’m betting you can’t guess the pathway that turned into “Spongebob riding a white horse past a bookshelf”). Some of those mnemonics have been in my brain for nearly a decade, and they’re as vivid and weird as ever. So, to the method of loci, I say “ole!” And please pass the pie.

This article is part of a series of collaborative posts with Sketchy, who specializes in learning through memory palaces. (Their glycolysis lesson is a full theme park ride with animatronic pirates for each substrate of the pathway!) Sketchy just published an article of their own about how practice and practice tests enhance your learning. To attack your MCAT prep with proven memory techniques and the best practice tests around, make sure to check out the Sketchy X Blueprint bundle!

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