Biochemistry is a heavily weighted subject on the MCAT, making up 25% of both the Chemical and Physical Foundations of Biological Systems and the Biological and Biochemical Foundations of Living Systems sections. This means approximately 30 questions across these two sections will be biochemistry-related.
To excel in biochemistry for the MCAT, you should focus on understanding the following high-yield topics:
1. Amino Acids, Peptides, and Proteins
* Structure and Properties: Memorize the 20 alpha-amino acids, including their structures, full names, three-letter codes, and single-letter codes. Understand their properties, such as how their charge changes with pH, and their classifications (e.g., polar, non-polar, charged, essential).
* Protein Structure: Understand the primary, secondary, tertiary, and quaternary structures of proteins, and the forces that stabilize them (e.g., peptide bonds, protein folding).
* Non-Enzymatic Protein Function: Be familiar with proteins that serve functions other than catalysis.
2. Enzymes and Enzyme Kinetics
* Enzyme Structure and Function: Know how enzymes work as catalysts, their classification by reaction type, and the mechanisms of catalysis.
* Enzyme Kinetics: Understand Michaelis-Menten kinetics, Lineweaver-Burk plots, enzyme inhibition (competitive, uncompetitive, mixed, non-competitive), and factors affecting enzyme activity (e.g., temperature, pH).
* Regulation of Enzyme Activity: Learn about different ways enzyme activity is controlled.
3. Metabolic Pathways and Energy Production
* Key Pathways: Master glycolysis, pyruvate oxidation, the Krebs cycle (citric acid cycle), oxidative phosphorylation, and gluconeogenesis.
* Details of Pathways: For each pathway, know the irreversible steps, rate-limiting enzymes, intermediates, and net ATP/NADH produced.
* Regulation and Connections: Understand how these pathways are regulated, their interconnections, and hormonal regulation (e.g., insulin, glucagon, epinephrine).
* Bioenergetics and Thermodynamics: Be familiar with principles of thermodynamics, including Gibbs Free Energy (ΔG) and its relation to spontaneity.
4. DNA, RNA, and Genetics
* Nucleic Acid Structure and Function: Understand the structure of DNA and RNA, including nucleotides, the sugar-phosphate backbone, hydrogen bonding, and complementary base pairing.
* Genetic Processes: Master DNA replication (including enzymes like DNA polymerase, ligase, primase, helicase, leading/lagging strands, Okazaki fragments), transcription (RNA polymerase, promoters, enhancers, termination signals, RNA processing like introns, exons, splicing, poly-A tails, 5' caps), and translation.
* Gene Regulation: Understand gene regulation in both prokaryotes (operons) and eukaryotes, including mutations and repair mechanisms.
5. Other Important Topics
* Carbohydrates: Understand carbohydrate structure and metabolism.
* Lipids: Learn about lipid types, their structure, function (e.g., cell membranes, energy storage, steroid hormones), and metabolism (e.g., fatty acid oxidation and synthesis).
* Biological Membranes: Understand their structure and function.
* Laboratory Techniques: Be familiar with common techniques such as gel electrophoresis, blotting methods (Southern, Northern, Western), PCR, DNA sequencing, and chromatography basics.
Study Strategies for Biochemistry:
* Focus on high-yield topics: Prioritize the most frequently tested concepts.
* Memorize strategically: For amino acids, know structures, classifications, and properties. For metabolic pathways, focus on the "big picture" and key control points rather than memorizing every single detail.
* Visualize and draw: Use diagrams and visuals to understand biochemical pathways and connections between molecules. Drawing pathways repeatedly can help solidify understanding.
* Practice problems: Engage with MCAT-style questions to refine problem-solving skills and apply theoretical knowledge to practical scenarios.
* Understand, don't just memorize: Focus on conceptual understanding and how concepts relate to each other.
* Use mnemonics and acronyms: These can be helpful for remembering complex information.
* Review regularly: Utilize spaced repetition to ensure retention of high-yield topics.