Step 1 Content | Biochemistry

General Biochemistry

- DNA structure, replication, repair - RNA transcription, processing, translation - Protein folding, post-translational modifications - Enzyme kinetics and regulation - Energy metabolism (ATP production, oxidative phosphorylation) - Carbohydrate, lipid, amino acid, nucleotide metabolism - Signal transduction pathways (MAPK, JAK-STAT, GPCR) - pH regulation and buffer systems

- Inborn errors of metabolism (e.g., phenylketonuria, homocystinuria) - Lysosomal storage diseases (e.g., Gaucher, Tay-Sachs, Niemann-Pick) - Mitochondrial disorders (e.g., MELAS, Leigh syndrome)

Hematopoietic & Lymphoreticular

- Heme biosynthesis and degradation - Iron metabolism and transport (ferritin, transferrin) - Purine and pyrimidine metabolism (nucleotide synthesis)

- Hemoglobinopathies (sickle cell disease, thalassemia) - Porphyria (acute intermittent porphyria, erythropoietic porphyria) - G6PD deficiency - Hyperuricemia and gout

Central & Peripheral Nervous

- Neurotransmitter biosynthesis and degradation (dopamine, serotonin, GABA, glutamate) - Brain energy metabolism (glucose, ketone bodies) - Blood-brain barrier and transport systems

- Neurodegenerative disorders (Alzheimer’s, Parkinson’s, Huntington’s) - Phenylketonuria, maple syrup urine disease - Tay-Sachs, Krabbe, metachromatic leukodystrophy - Wilson disease (copper metabolism defect)

Skin & Connective Tissue

- Collagen and elastin biosynthesis - Keratinization and skin barrier function - Melanin biosynthesis (tyrosinase, albinism)

- Ehlers-Danlos syndrome, Marfan syndrome - Osteogenesis imperfecta - Scurvy (vitamin C deficiency) - Albinism, vitiligo

Musculoskeletal

- Muscle contraction biochemistry (actin, myosin, troponin) - Bone mineralization and calcium metabolism - ATP production in muscle (glycolysis, oxidative phosphorylation)

- Duchenne muscular dystrophy - Rickets, osteomalacia - Gout (uric acid metabolism disorder) - McArdle disease (glycogen storage disorder)

Respiratory

- Oxygen transport and hemoglobin function - Acid-base balance and CO2 buffering - Surfactant synthesis and lung biochemistry

- Chronic obstructive pulmonary disease (COPD) - Respiratory acidosis/alkalosis - Neonatal respiratory distress syndrome (deficiency of surfactant)

Cardiovascular

- Lipid metabolism (cholesterol, triglycerides, lipoproteins) - Coagulation cascade biochemistry - Nitric oxide and vascular regulation

- Familial hypercholesterolemia - Atherosclerosis and dyslipidemias - Hypertension (renin-angiotensin-aldosterone system) - Homocystinuria (vascular complications)

Gastrointestinal

- Digestion and absorption of macronutrients - Bile acid metabolism and enterohepatic circulation - Pancreatic enzyme biochemistry

- Lactose intolerance - Celiac disease (gluten metabolism) - Wilson disease (copper transport disorder) - Gilbert syndrome (bilirubin metabolism defect)

Renal/Urinary

- Electrolyte and fluid homeostasis - Acid-base balance and renal buffering - Urea cycle and nitrogen excretion

- Renal tubular acidosis - Fanconi syndrome - Cystinuria (amino acid transport defect) - Hyperammonemia (urea cycle disorders)

Reproductive

- Steroid hormone biosynthesis (estrogen, testosterone) - Follicular and luteal phase hormonal regulation - Sperm metabolism and capacitation

- Congenital adrenal hyperplasia - Aromatase deficiency - Klinefelter and Turner syndromes - Polycystic ovarian syndrome (PCOS)

Endocrine

- Hormone synthesis, secretion, receptor signaling - Insulin and glucose metabolism - Thyroid hormone biosynthesis - Parathyroid hormone and calcium metabolism

- Diabetes mellitus (Type 1 and Type 2) - Cushing syndrome (cortisol excess) - Addison disease (adrenal insufficiency) - Hypothyroidism and hyperthyroidism