All courses · core course
Biochemistry
Thirty lessons that follow a one-semester biochemistry course, from water and weak bonds to the integration of metabolism.
9 units · 30 lessons
Unit 1 · Foundations
- Interlude · Alchemy & Vitalism Vitalism: How Chemistry Captured Life Before biochemistry could begin, one idea had to die — this is its seventy-year retreat.
- Introduction to Biochemistry & the Cell Introduction to Biochemistry and Cell Biology: Compartments Create Control Why can one missing enzyme kill a child before age three? The answer is compartments.
- Water and Weak Interactions Water, Weak Bonds, and the Generation of Order The second law says everything should fall apart. Water's own disorder pays for life's order.
Unit 2 · Proteins
- Amino Acids Amino Acids: How One Side Chain Decides Everything The R group sets the chemistry — charge, pKa, and the Glu→Val swap behind sickle cell all fall out of it.
- Protein Three-Dimensional Structure Protein Three-Dimensional Structure: How a Sequence Folds Itself More shapes than the age of the universe allows, folded in milliseconds — the answer is constraints.
- Techniques in Protein Biochemistry Techniques in Protein Biochemistry: Purify It, Then Prove It Pull one protein out of a soup of ten thousand others — then prove you got it.
Unit 3 · Enzymes & Binding
- Enzymes and Bioenergetics Basic Concepts of Enzyme Action Can an enzyme make an impossible reaction happen? No — it can only make a possible one fast.
- Mechanisms and Inhibitors Enzyme Kinetics: The Michaelis–Menten Model Why doesn't doubling the substrate keep doubling the rate? Enzymes saturate.
- Molecular Recognition & Allostery Protein Binding, Molecular Recognition, and Allostery One O₂ pulls the iron 0.4 Å; that twitch rotates the whole tetramer. Cooperativity is mechanics.
Unit 4 · Sugars, Lipids & Membranes
- Carbohydrates & the Sugar Code Carbohydrates: One Hydroxyl Decides Storage or Structure Flip a single hydroxyl on glucose and you decide whether the polymer feeds you or holds a plant up.
- Lipids & Membrane Architecture Lipids: The Building Blocks That Refuse to Polymerize Shape is destiny: a single cis double bond is the difference between lard and olive oil.
- Membranes & Transport Membranes: The Impermeable Sheet That Builds Itself Cystic fibrosis is, at bottom, a story about one protein that never reaches the right membrane.
Unit 5 · Signaling & Digestion
- Cell Signaling Signal-Transduction Pathways: How Cells Compute With Molecular Switches One epinephrine molecule mobilizes millions of glucose molecules; amplification is the whole story.
- Digestion & Absorption Digestion: Turning a Meal into Cellular Biomolecules Digestion is one chemical reaction run three ways — and trypsin is the master switch.
Unit 6 · Central Metabolism
Play these pathways. Wire the cell, run the regulators through a fast, and diagnose a broken enzyme in the Metabolism Arcade.- Metabolism: Foundations Metabolism: Basic Concepts and Design Metabolism is an energy economy; learn its grammar before any pathway teaches its vocabulary.
- Glycolysis Glycolysis: The Investment-and-Payoff Pathway Why does a cell spend ATP to make ATP? The first three steps are a deliberate investment.
- Glucose Homeostasis Gluconeogenesis: Pushing Glucose Back Uphill Four new enzymes, three compartments, real ATP spent uphill: how the body builds glucose from scratch.
- The Citric Acid Cycle The Pyruvate Dehydrogenase Complex: The One-Way Gate to the Cycle One machine, three enzymes, five coenzymes, a 14 Å swinging arm — and no way back once carbon walks through.
- The Citric Acid Cycle The Citric Acid Cycle: Harvesting Electrons The citric acid cycle does not make ATP. Its real product is high-energy electrons.
- Cellular Respiration Oxidative Phosphorylation: The Electron-Transport Chain Electron flow and ATP synthesis are two separate machines linked by one thing: the proton gradient.
- Cellular Respiration The Proton-Motive Force and ATP Synthase Peter Mitchell saw the proton gradient in 1961, was ridiculed for seventeen years, and was vindicated.
Finished the unit? Take the unit review →
Unit 7 · Photosynthesis
- Photosynthesis Photosynthesis: The Light Reactions Two photon-driven uphill boosts, wired so water splits, oxygen leaves, and NADPH gets made.
- Photosynthesis The Calvin Cycle: Fixing Carbon from Thin Air Every carbon in every sugar, protein, and strand of DNA on Earth was pulled out of thin air by this loop.
Unit 8 · Fuels, Fat & Nitrogen
Play these pathways. Wire the cell, run the regulators through a fast, and diagnose a broken enzyme in the Metabolism Arcade.- Glucose Homeostasis The Pentose Phosphate Pathway: NADPH and Five-Carbon Sugars It makes no ATP, and that is the point: NADPH and ribose-5-phosphate are the products that matter.
- Lipid Metabolism Fatty Acid Degradation: The β-Oxidation Spiral Fat comes apart two carbons at a time — and palmitate's ~106 ATP only balance if you keep the books.
- Lipid Metabolism Fatty Acid Synthesis: Building the Chain Two Carbons at a Time Cytoplasm, ACP, NADPH: three choices that keep building fat from colliding with burning it.
- Lipid Metabolism Lipid Synthesis: Building Cholesterol from Acetyl-CoA From two-carbon acetate to a 27-carbon ring: master HMG-CoA reductase and the statins follow.
- Nitrogen Metabolism Protein Turnover and Amino Acid Catabolism: Tag, Recognize, Destroy, Recycle A protein's lifespan runs from minutes to a lifetime, set by tags the cell reads and acts on.
Finished the unit? Take the unit review →
Unit 9 · Supplements
- Supplement · Nucleotide Metabolism Nucleotide Metabolism: Build It, Recycle It, or Pay in Uric Acid Nucleotides are too expensive to throw away — gout, Lesch-Nyhan, and allopurinol live where recycling breaks.
- Supplement · Integration of Metabolism Integration of Metabolism: How the Body Switches Fuels Fed, fasting, starving: two hormones switch every pathway in this course on and off in a timed sequence.