LS 1a: Life Sciences
Chemistry, molecular biology, and cell biology taught as one integrated story, the way Harvard's LS 1a teaches it.
12 units · 105 topics · 470 questions
The thermodynamics, equilibrium, and water chemistry a cell runs on before any biology happens at all.
Energy and Entropy in Living Systems · Gibbs Free Energy and Whether a Reaction Runs · Coupled Reactions and ATP-Driven Chemistry · Chemical Equilibrium and Le Chatelier's Principle in the Cell · +5 more
Carbohydrates, lipids, proteins, and nucleic acids as four different answers to the same two chemical moves.
Building Polymers by Condensation and Hydrolysis · Carbohydrate Structure and Glycosidic Bonds · Lipid Structure: Fatty Acids and Triglycerides · Amino Acid Structure and Side-Chain Chemistry · +2 more
How a chain of amino acids becomes a working machine, with hemoglobin as the worked example of structure driving function.
Primary Structure: The Sequence as Information · Secondary Structure: Alpha Helices and Beta Sheets · Tertiary Structure and the Forces That Fold a Protein · Hydrophobic Collapse and the Folding Funnel · +6 more
How a protein bends the odds of a reaction, measures its own speed limit, and gets throttled by inhibitors and feedback.
Activation Energy and the Transition State · How an Active Site Stabilizes the Transition State · Enzyme Specificity: Lock-and-Key Versus Induced Fit · Cofactors and Coenzymes · +6 more
Why a bilayer builds itself, what actually crosses it, and how a cell spends energy to move things the wrong way.
Amphipathic Lipids and Bilayer Self-Assembly · Membrane Fluidity, Cholesterol, and Fatty Acid Saturation · Membrane Proteins: Integral and Peripheral · Simple Diffusion Across a Membrane · +6 more
ATP as a currency, not a battery, and the first pathway every cell uses to cash it in from glucose.
ATP Structure and Hydrolysis · Why ATP Hydrolysis Releases Free Energy · Redox Reactions and NAD+/NADH · Glycolysis: The Energy Investment Phase · +4 more
Where the real ATP payoff comes from: a spinning loop of oxidation feeding a proton gradient that spins a molecular motor.
Pyruvate Oxidation and Acetyl-CoA Formation · The Citric Acid Cycle: An Overview of the Loop · Tracking Carbons and Electrons Through the Citric Acid Cycle · The Electron Transport Chain · +4 more
The mirror image of respiration, and how a cell decides whether to store fuel or burn it.
Capturing Light: Chlorophyll and the Light-Dependent Reactions · Splitting Water and Building a Proton Gradient in the Chloroplast · The Calvin Cycle and Carbon Fixation · Why Photosynthesis and Respiration Are Chemical Mirror Images · +2 more
The chemistry that makes base pairing specific, and the machinery that copies, reads, and translates it into protein.
Why Base Pairing Is Chemically Specific · The Double Helix Structure · Semiconservative Replication · DNA Polymerase and the Replication Fork · +6 more
How a cell decides which genes to read, from a bacterium's operon to a human genome folded around histones.
The Lac Operon and Inducible Gene Expression · The Trp Operon and Repressible Gene Expression · Transcription Factors and How They Find Their DNA Targets · Chromatin Structure: DNA Wrapped Around Histones · +3 more
How a single molecule outside a cell turns into a coordinated, massively amplified response inside it.
Why Cells Need Receptors Instead of Direct Entry · G-Protein-Coupled Receptors and the On/Off Switch · Second Messengers: cAMP and Amplification · Calcium as a Signaling Ion · +5 more
How a cell decides to divide, what happens when that decision breaks, and the lab tools that let us watch any of it directly.
The Phases of the Cell Cycle · Checkpoints and the Decision to Divide · Cyclins and Cyclin-Dependent Kinases · p53 and the Guardian-of-the-Genome Checkpoint · +8 more