Most Commonly Missed Concept #1: Michaelis-Menten Kinetics

Overview: After Amino Acids and the Metabolic Pathways, Michaelis-Menten Kinetics is easily the next most commonly tested topic on the MCAT. In fact, you are likely to see about as many Michaelis-Mentin Kinetics questions on test day as you are to see Organic Chemistry questions. Yet, Kaplan devotes an entire book to Organic Chemistry and only part of a chapter to Michaelis-Menten Kinetics. That is the primary purpose of this lesson as well as the primary purpose of this course. My goal is to cover some of the most commonly tested (yet missed) concepts, and Michaelis-Menten Kinetics easily ranks at the top of the list. You’ll want to know this lesson inside and out.


For starters, what is the purpose of Michaelis-Menten Kinetics? Simply put, the goal is to characterize the speed at which an enzyme is able to convert a substrate into its product. Remember that enzymes will bind to their substrate and then convert it into its product(s) as seen in the following simplified diagram:

One reason that Michaelis-Menten Kinetics can be so hard for students to grasp is that professors, books, and videos make the topic overly complicated by trying to teach you the derivations of the various equations and charts, etc. Let me fill you in on a little secret — The MCAT could care less about these useless details! 🙂 We are going to maintain our focus on the essential features of this topic, the stuff that the MCAT will actually test you on.

With our basic understanding of this enzymatic process, let’s take a look at the standard Michaelis-Menten graph (see image to the right). On the x-axis, you have the substrate concentration ([S]), and on the y-axis, you have the initial velocity of the reaction (Vo). The purpose of this graph is to determine how much substrate we need to add before this reaction will no longer proceed any faster. At what point will the enzymes not be able to convert the substrate into product any faster? It is at this point that all the enzymes will be “saturated” (filled) with substrate. This is what we call Vmax, the maximum speed of the reaction. On the graph, Vmax is where the hyperbolic curve flattens out.

Keep in mind that at Vmax, adding more substrate will do nothing because all the enzymes are saturated. Typically the only way to increase Vmax is to increase the amount of enzyme. This is a well-tested idea, so don’t forget it — Increasing the substrate concentration will NOT increase Vmax.

Something that can be hard for students to grasp is the idea of Km, the Michaelis-Menten constant. Let’s lay it out nice and simple. Km is the…

To access the rest of this lesson as well as the remaining 9 Most Commonly Missed Concepts, simply enroll today!

Quizlet Practice:

Associated Questions from the AAMC:

  • Question 7 of the Biology/Biochemistry Section of the Official Guide Questions.
  • Questions 14 and 30 of the Chemistry/Physics Section of the Official Guide Questions.
  • Questions 33, 54, 55, 73, 75, and 90 of the Biology/Biochemistry Section of the Section Bank.
  • Questions 30, 33, 39, 48, 49, 50, 55, 56, 75, 77, 95, and 99 of the Chemistry/Physics Section of the Section Bank.
  • Question 20 of the Chemistry/Physics Section of the Sample Test.
  • Questions 23 through 25 of the Biology/Biochemistry Section of the Sample Test.
  • Question 8 of the Chemistry/Physics Section of Practice Exam 2.

To access the rest of this lesson as well as the remaining 9 Most Commonly Missed Concepts, simply enroll today!


MCAT Prep Course - MCAT Tutor
MCAT Prep Course - MCAT Questions
MCAT Prep Course - MCAT CARS
MCAT Prep Course - MCAT Behavioral Science

How we Matched up the Khan Academy Passages with the eCourse Lessons

Each lesson of the eCourse contains links to 1 to 5 Khan Academy science passages for the purpose of providing you with non-AAMC material to practice your science passage reading skills on. By completing all the linked passages within every lesson, you will have finished all the freely available Khan Academy science passages.

To match up the Khan Academy Science Passages with the eCourse lessons, we carefully examined the passage and question content of each one. Then we decided which lesson of the eCourse best correlated with that content. You may notice that some passages don’t match up perfectly with the current lesson. If they don’t match up with the current lesson, they should match up with one of the previous lessons in the module. We did this carefully so that you could practice your science passage reading skills on passages that contain the content you’ve already learned.

Why we don’t recommend non-AAMC CARS practice questions

We recommend practicing CARS by reading non-AAMC CARS passages but not doing the associated practice problems. The reason we don’t recommend doing the practice problems is because the MCAT is written by the AAMC. They have a very unique style in which they write CARS practice questions that third-party companies (try as they might) are unable to replicate. When students spend time on non-AAMC CARS practice problems, they get familiar with the wrong style of questioning, leading them to overthink and incorrectly respond to the questions written by the AAMC. Thus, it is in your best interest to solely practice on AAMC CARS practice questions.

That said, we highly recommend practicing your reading skills on non-AAMC CARS passages. In our Ultimate CARS Strategy Course, we provide you with 1,000 free CARS passages and 100+ homework assignments, giving you ample material to practice on. Reading countless passages while practicing the proper reading habits and strategies will prepare you well to conquer the CARS section as it was written by the AAMC.

Which books do the lessons match up with?

The books we use in each lesson are linked below. We plan to stick with these older editions of the books since very little has changed and the older editions are much more affordable:

First Edition of the Kaplan 7-book Series
First Edition of the Princeton 7-book Series

Do the chapters match up perfectly?

The Kaplan Books, Princeton Books, and Khan Academy Videos were all produced by different authors. For this reason, there are some chapters in the Kaplan Book or Princeton Book that are not even found in the Khan Academy Videos and vice versa. For instance, the Kaplan and Princeton Books have chapters that cover certain experimental procedures that the Khan Academy Videos do not cover.

Our goal in matching up the books with the videos was to correlate the content as best as possible while also covering ALL the content from every resource. For this reason, when nothing in the Kaplan Books matched up with one of the video playlists, instead of leaving the reading assignment for Kaplan blank, we inserted material that did not fit in anywhere else (i.e. one of those chapters on an experimental procedure that was not covered by Khan Academy). So, when the assignment doesn’t appear to match up right, please know that this was intentional.

*If you follow the reading assignments outlined, you will finish the entire Kaplan 7-book series and/or Princeton 7-book series by the time you finish all 10 content modules.

Do the sections match up perfectly?

If the sections assigned in our eCourse do not match up with the sections contained in your content review book, you may have a different edition. The sections should still match up the large majority of the time, but in the rare instance that they don’t, I’d recommend simply reading sections that do match up and saving the ones that do not for a future lesson.

MCAT Launchpad Required!

Before jumping into our free eCourse, you’ll need to complete orientation by watching MCAT Launchpad. During this free 35-minute intro session with Head Tutor Andrew, you’ll learn 6 Keys to Earning a Top MCAT Score, the 5 Essential Elements of an Effective Study Plan, 12 Tips for Taking the Best MCAT Study Notes, and more! Andrew will also provide you with a detailed overview of the Free MCAT Prep Course, teaching you how to get started.

Are you sure you want to skip today's special offer?

You will forfeit your 30% off coupon by continuing with Free Forever.