Yes, biochemistry is on the MCAT, and it’s one of the most heavily tested subjects on the exam. First-semester biochemistry makes up 25% of two of the four scored sections, making it a subject you’ll encounter throughout your test day. Understanding exactly where and how biochemistry appears will help you prioritize your study time effectively.
Where Biochemistry Appears on the MCAT
Biochemistry shows up in two of the MCAT’s four scored sections. In the Biological and Biochemical Foundations of Living Systems section, first-semester biochemistry accounts for 25% of the content. The remaining 75% of that section draws from introductory biology (65%), introductory general chemistry (5%), and introductory organic chemistry (5%).
Biochemistry also makes up 25% of the Chemical and Physical Foundations of Biological Systems section. That means across both science-heavy sections, you’re looking at a significant chunk of questions rooted in biochemistry. No other subject besides introductory biology carries this much weight across multiple sections.
What Biochemistry Topics Are Tested
The AAMC designs these questions at the level of a typical first-semester undergraduate biochemistry course. You won’t see advanced topics from upper-division electives, but you do need a solid grasp of the foundational material. The most commonly tested areas include amino acid structure and properties, protein folding and function, enzyme kinetics (how enzymes speed up reactions and how inhibitors slow them down), and the major metabolic pathways like glycolysis, the Krebs cycle, oxidative phosphorylation, gluconeogenesis, and beta-oxidation of fatty acids.
Beyond memorizing pathways and structures, expect questions on molecular biology topics that overlap with biochemistry. DNA replication, transcription, translation, and gene regulation all fall into this territory. You should also be comfortable with lipid structure and membrane biology, carbohydrate chemistry, and how small molecules like hormones and signaling molecules interact with proteins.
How Biochemistry Questions Actually Look
Most MCAT questions aren’t straightforward recall. They’re passage-based, meaning you’ll read a short research-style passage and then answer several questions that require you to apply your knowledge to new information. Biochemistry questions frequently blend with other disciplines, which is what makes them challenging.
For example, a passage might describe a gene deletion experiment and ask you to predict how the loss of a specific enzyme would affect a metabolic pathway. Another passage could present data from a Western blot or mass spectrometry experiment and require you to interpret the results using your understanding of protein structure or enzyme function. You might also see passages that connect biochemical processes like N-glycosylation (the attachment of sugar chains to proteins) to broader topics like lipid biosynthesis or cellular signaling.
This integration means you can’t study biochemistry in isolation. You need to understand how biochemical concepts connect to experimental techniques like gel electrophoresis, chromatography, and restriction enzyme digestion. Practicing with passage-based questions that cross disciplinary boundaries is essential for building this skill.
Coursework That Prepares You
At minimum, you should complete a first-semester biochemistry course before taking the MCAT. This is the level the exam targets, and skipping it puts you at a serious disadvantage given how much of the test relies on this material. Most pre-med students take biochemistry after completing general chemistry, organic chemistry, and introductory biology, which gives you the background needed to understand enzyme mechanisms, molecular interactions, and metabolic regulation.
If your school offers a two-semester biochemistry sequence, the first semester alone covers the vast majority of what the MCAT tests. Topics from a second semester, like advanced signal transduction cascades or detailed lipid metabolism beyond the basics, rarely appear. That said, the deeper your understanding of first-semester material, the more comfortable you’ll feel interpreting unfamiliar passages on test day.
How to Study Biochemistry for the MCAT
Start by building a strong foundation in amino acids. Know all 20 standard amino acids by name, structure, three-letter code, one-letter code, and chemical properties (charged, polar, nonpolar). This knowledge feeds into virtually every other biochemistry topic on the exam, from enzyme active sites to protein folding to laboratory techniques like gel electrophoresis.
Next, focus on metabolic pathways. You don’t need to memorize every intermediate in every pathway, but you should know the inputs, outputs, key regulatory enzymes, and where each pathway occurs in the cell. Understanding the logic of regulation matters more than rote memorization. Why does phosphofructokinase slow down when ATP levels are high? Because the cell doesn’t need more energy. That kind of reasoning is exactly what passage-based questions reward.
Enzyme kinetics is another high-priority area. Be comfortable with Michaelis-Menten kinetics, Lineweaver-Burk plots, and the differences between competitive, uncompetitive, and noncompetitive inhibition. Know how each type of inhibitor changes Vmax (the maximum reaction rate) and Km (the substrate concentration at which the reaction runs at half its maximum speed).
Finally, practice interpreting experimental data. The MCAT doesn’t just test whether you know biochemistry. It tests whether you can use biochemistry to make sense of an experiment you’ve never seen before. Work through practice passages that include figures, graphs, and unfamiliar experimental setups. The more you practice reading like a scientist, the faster and more accurately you’ll move through these questions on test day.