BiochemStep is a focused USMLE Step 1 biochemistry question bank covering metabolism, genetics, molecular biology, laboratory techniques, nutrition, and integrated physiology.
No credit card required.
Focused practice for the mechanism-heavy foundational science questions that often sit underneath clinical vignettes.
Practice the multi-step logic behind Step 1 vignettes: recognize the presentation, identify the pathway defect, and reason through the biochemical consequence.
BiochemStep includes focused Step 1-style questions across recurring foundational science mechanisms, organized into timed and tutor-style practice blocks.
Correct and incorrect answer explanations are written to help you rule out similar conditions, pathways, and mechanisms on future questions.
BiochemStep focuses on recurring foundational science concepts that appear across organ-system questions, including metabolism, genetics, molecular biology, laboratory techniques, nutrition, acid-base physiology, and homeostasis.
Built around how Step 1 tests
Each question is designed to connect the presentation to the underlying pathway, molecular defect, physiologic change, or treatment mechanism.
Coverage by Foundational Science Domain
Amino acid catabolism, nitrogen handling, urea cycle chemistry, heme-related pathways, and inherited metabolic disease mechanisms.
Glycolysis, gluconeogenesis, glycogen metabolism, monosaccharide metabolism, the pentose phosphate pathway, and metabolic regulation.
Glycogen synthesis, glycogen breakdown, lysosomal glycogen handling, fasting hypoglycemia, exercise intolerance, and organ-specific storage patterns.
Fatty acid oxidation, ketone body metabolism, cholesterol and lipoprotein regulation, lipid transport, and pathway-targeted pharmacology.
Purine and pyrimidine synthesis, salvage pathways, nucleotide degradation, antimetabolite mechanisms, and pharmacogenomic toxicity.
Water-soluble and fat-soluble vitamin mechanisms, cofactor-dependent reactions, trace elements, hematologic effects, and neurologic consequences.
Protein-energy malnutrition, micronutrient deficiency, refeeding physiology, and nutrition-linked biochemical consequences.
DNA repair, transcription, RNA processing, translation, chromatin regulation, protein folding, genome maintenance, and toxin effects on protein synthesis.
Molecular diagnostics, cytogenetics, sequencing, immunologic detection, protein detection, gene-editing concepts, and separation methods.
Inheritance patterns, chromosomal disorders, imprinting, trinucleotide repeats, lysosomal biology, cell signaling, apoptosis, and tumor suppressor pathways.
Fed and fasting metabolism, acid-base physiology, oxidative phosphorylation, hemoglobin biochemistry, membrane transport, and hormone-mediated regulation.
Michaelis-Menten reasoning, Km, Vmax, inhibitor patterns, irreversible inhibition, allosteric regulation, and clinically relevant enzyme defects.
Red-cell biochemistry, coagulation regulation, complement biology, phagocyte function, lymphocyte signaling, antigen processing, and immune-effector mechanisms.