Biochemistry

Introduction

Biochemistry studies the chemical structures, reactions, energy transformations, and information-processing mechanisms that make living systems possible. It connects Chemistry with Biology by asking how molecular properties generate cellular functions. At university level, biochemistry is not mainly a catalogue of molecules. It is a way of reasoning across several scales: from electrons and chemical bonds, through proteins and metabolic networks, to cells, tissues, and whole organisms.

In this aiMOOC, you will work with the molecular logic of life: water and noncovalent interactions, acids and bases, thermodynamics, proteins, enzymes, carbohydrates, lipids, nucleic acids, metabolism, bioenergetics, and experimental methods. You will also practice interpreting equations, pathways, graphs, and biochemical evidence. The course assumes introductory chemistry and biology, including familiarity with covalent bonding, moles, equilibrium, cells, and basic genetics.

The cell membrane is an excellent starting point for biochemical thinking. Its lipid bilayer is assembled by the hydrophobic effect, while membrane proteins carry out transport, signaling, adhesion, and catalysis. A biological structure therefore emerges from both molecular composition and physical interactions.

Why Biochemistry Matters

Biochemistry explains how nutrients are converted into usable energy, how enzymes accelerate reactions, how DNA stores information, how RNA and proteins implement that information, and how molecular defects can lead to disease. It supports fields as different as Molecular biology, Medicine, Pharmacology, Biotechnology, Nutrition, Neuroscience, Agriculture, and Systems biology.

A useful habit is to ask four questions whenever you encounter a biochemical process: What molecules are involved? What chemical transformation occurs? Where does the energy come from or go? How is the process regulated? These questions help you connect mechanism with function instead of memorizing isolated facts.

Learning Outcomes and Prerequisites

By the end of the course, you should be able to explain how molecular structure influences biochemical function, predict qualitative effects of pH and noncovalent forces, analyze enzyme kinetic data, connect free-energy changes with reaction coupling, trace carbon and electron flow through central metabolism, relate nucleic-acid chemistry to information transfer, and evaluate the strengths and limitations of common biochemical experiments.

You should also be able to transfer these ideas to unfamiliar problems. For example, if a mutation changes a charged amino-acid side chain in an enzyme, you should be able to propose consequences for folding, substrate binding, catalysis, or regulation and then design an experiment that could distinguish among those possibilities.

The Molecular Logic of Life

Water, Noncovalent Interactions, and Molecular Recognition

Water is the dominant solvent of most cells. Its polarity and capacity for hydrogen bonding strongly influence the organization of biomolecules. Ionic interactions, hydrogen bonds, van der Waals contacts, and the hydrophobic effect are individually modest in energy compared with many covalent bonds, but their combined effects can stabilize highly specific molecular structures and interactions.

The hydrophobic effect is especially important. Nonpolar groups tend to cluster away from water, which contributes to membrane formation and to the folding of many globular proteins. Molecular recognition usually depends on complementary shape, charge distribution, hydrogen-bond donors and acceptors, and dynamic flexibility. Binding is therefore neither purely geometric nor completely rigid.

Biochemical interactions are also concentration-dependent. A weak interaction can become important when reactants are locally concentrated, while a strong interaction can become transient if competitors are abundant. This is one reason why cellular context matters when you interpret data obtained from purified molecules.

Acids, Bases, pH, and Buffers

Many biomolecules contain ionizable groups. Their protonation states influence charge, solubility, binding, catalysis, and membrane permeability. For a weak acid HA that dissociates to H+ and A−, the Henderson-Hasselbalch equation is:

$p H = p K_{a} + \log \frac{[A^{-}]}{[H A]}$

When pH equals pKa, the protonated and deprotonated forms are present at equal concentrations. Near a group's pKa, relatively small changes in pH can substantially change its protonation state. Buffers resist changes in pH most effectively when the solution pH lies near the pKa of the buffering species.

In proteins, the local environment can shift the apparent pKa of an ionizable side chain. A residue buried in a hydrophobic pocket or placed near another charged group may behave differently from the same amino acid free in solution. Such pKa shifts are often central to enzyme catalysis.

Thermodynamics and Free Energy

Biochemical reactions obey the laws of thermodynamics. At constant temperature and pressure, the Gibbs free-energy change is:

$Δ G = Δ H - T Δ S$

A process with a negative ΔG is thermodynamically favorable in the stated conditions, but thermodynamic favorability does not specify how fast the reaction occurs. Reaction rate is a kinetic question. Enzymes can accelerate reactions by lowering the activation free-energy barrier without changing the overall ΔG or the equilibrium constant.

The biochemical standard free-energy change, often written ΔG°′, is related to the equilibrium constant. Inside cells, however, actual concentrations usually differ from standard-state values, so the actual ΔG depends on the reaction quotient. Cells exploit this dependence by maintaining concentration gradients and by coupling unfavorable reactions to strongly favorable ones.

ATP is a central coupling molecule. Hydrolysis of ATP can provide free energy that is coupled to otherwise unfavorable processes such as biosynthesis, active transport, and mechanical work. The phrase “high-energy bond” is a shorthand and can be misleading: energy release comes from the overall difference in free energy between reactants and products, not from energy being stored in a single bond in isolation.

Biomolecules: Structure Creates Function

Amino Acids and Proteins

Proteins are polymers built from amino acids joined by peptide bonds. Most protein amino acids contain an amino group, a carboxyl group, a hydrogen atom, and a variable side chain attached to the alpha carbon. With the exception of glycine, the standard amino acids are chiral, and ribosomally synthesized proteins predominantly use the L configuration.

Side-chain chemistry gives amino acids their functional diversity. Nonpolar side chains often contribute to hydrophobic cores; polar side chains can participate in hydrogen bonds; acidic and basic side chains can carry charge; cysteine can form disulfide bonds; and residues such as serine, threonine, and tyrosine are common sites of reversible phosphorylation.

Protein structure is conventionally discussed at four levels. Primary structure is the amino-acid sequence. Secondary structure includes local conformations such as alpha helices and beta sheets, largely stabilized by backbone hydrogen bonding. Tertiary structure describes the overall three-dimensional fold of a polypeptide. Quaternary structure describes assemblies of multiple polypeptide subunits.

Protein folding is driven by many interactions and constrained by the amino-acid sequence, solvent, temperature, pH, molecular crowding, and often helper proteins called chaperones. A folded protein is not a rigid object; it occupies an ensemble of conformations. Function often depends on controlled conformational changes, which are central to catalysis, signaling, transport, and allosteric regulation.

Protein denaturation disrupts higher-order structure without necessarily cleaving peptide bonds. Heat, extreme pH, organic solvents, detergents, or chaotropic agents can destabilize noncovalent interactions. Whether a denatured protein can refold depends on the protein and the conditions.

Carbohydrates, Lipids, and Membranes

Carbohydrates serve as fuels, structural materials, recognition elements, and components of nucleotides. Monosaccharides can cyclize in solution, creating alpha and beta anomers. Glycosidic bonds connect monosaccharides into oligosaccharides and polysaccharides. The stereochemistry and linkage pattern strongly affect biological properties: glycogen and cellulose are both glucose polymers, yet their different glycosidic linkages produce very different structures and functions.

Lipids include fatty acids, triacylglycerols, phospholipids, sphingolipids, sterols, and many signaling molecules. Because many lipids are amphipathic, they self-organize into bilayers and other structures in water. Membrane fluidity depends on lipid composition, acyl-chain length, degree of unsaturation, temperature, and sterols such as cholesterol.

Membranes are selective barriers and dynamic platforms. Integral membrane proteins can act as channels, transporters, receptors, or enzymes, while peripheral proteins associate more loosely. The electrochemical gradients maintained across membranes store potential energy and are essential for processes such as nerve signaling and oxidative phosphorylation.

Nucleotides and Nucleic Acids

Nucleotides contain a nitrogenous base, a pentose sugar, and one or more phosphate groups. DNA generally uses deoxyribose and the bases adenine, guanine, cytosine, and thymine; RNA generally uses ribose and substitutes uracil for thymine. Nucleotides have roles beyond nucleic acids: ATP and GTP transfer chemical potential, cyclic nucleotides act in signaling, and nucleotide-derived cofactors such as NAD+ participate in redox chemistry.

DNA's phosphodiester backbone gives each strand directionality. Complementary base pairing and stacking interactions stabilize the double helix, while antiparallel strand orientation is essential to replication and transcription mechanisms. RNA is chemically and structurally diverse; it can form complex three-dimensional folds, recognize ligands, catalyze reactions, and regulate gene expression.

Enzymes and Biochemical Kinetics

Catalysis and Transition-State Stabilization

Enzymes are biological catalysts, usually proteins but sometimes RNA. They increase reaction rates by lowering the activation free-energy barrier. They do not make an unfavorable equilibrium favorable, and they do not change the equilibrium constant. Instead, they provide a reaction pathway in which the transition state is reached more readily.

Substrate binding can involve an induced-fit response, in which interactions with the substrate favor a catalytically productive enzyme conformation. Modern views also emphasize conformational selection: enzymes fluctuate among conformations, and ligands can preferentially bind particular members of that ensemble.

Catalytic strategies include acid-base catalysis, covalent catalysis, metal-ion catalysis, electrostatic stabilization, proximity and orientation effects, and preferential stabilization of the transition state. Enzymes often combine several strategies in a single active site.

Michaelis-Menten Kinetics

For a simple one-substrate mechanism,

$E + S ⇌ E S \to E + P$

the Michaelis-Menten equation for initial velocity is:

$v_{0} = \frac{V_{max} [S]}{K_{M} + [S]}$

At low substrate concentration, velocity is approximately proportional to [S]. At high substrate concentration, the enzyme becomes saturated and velocity approaches Vmax. Under the simple mechanism, $V_{max} = k_{c a t} [E]_{T}$ , so kcat is the turnover number under saturating substrate conditions.

KM has units of concentration and is the substrate concentration at which the initial velocity equals half Vmax for the Michaelis-Menten model. It is not universally identical to a substrate dissociation constant. For the simple mechanism, its value depends on microscopic rate constants, so interpreting KM directly as “affinity” can be wrong unless additional conditions are satisfied.

The ratio $k_{c a t} / K_{M}$ is the specificity constant and is especially informative at low substrate concentration. Comparing kinetic parameters can reveal how mutations, environmental changes, or inhibitors alter catalytic behavior.

Inhibition, Allostery, and Regulation

Competitive inhibitors bind in a way that prevents productive substrate binding; in the simplest Michaelis-Menten treatment, they increase the apparent KM while leaving Vmax unchanged. Pure noncompetitive inhibition lowers Vmax without changing KM. Uncompetitive inhibition lowers both apparent KM and Vmax by the same factor. Many real inhibitors show mixed behavior, so data should be fitted to mechanistically appropriate models rather than forced into idealized categories.

Allosteric enzymes are regulated by ligands that bind at sites distinct from the active site and alter conformational populations. Their velocity curves can be sigmoidal rather than hyperbolic, especially when cooperative binding occurs. Feedback inhibition uses pathway products to regulate earlier steps, allowing metabolism to respond efficiently to cellular demand.

When you analyze kinetic data, distinguish between an observation and a mechanistic claim. A changed Vmax or KM can suggest possibilities, but mechanism requires additional evidence such as binding measurements, structural data, mutagenesis, or product-pattern analysis.

Bioenergetics and Metabolism

ATP, Redox Reactions, and Metabolic Coupling

Metabolism is the coordinated network of chemical reactions that sustains life. Catabolism converts complex molecules into simpler products while capturing part of the released free energy. Anabolism uses energy and reducing power to build cellular components. These categories are useful, but many pathways are amphibolic and participate in both degradation and biosynthesis.

Oxidation-reduction reactions transfer electrons. Cofactors such as NAD+/NADH and FAD/FADH2 carry reducing equivalents between reactions. NADPH is used extensively for reductive biosynthesis and antioxidant defense. A central biochemical skill is to track not only carbon atoms but also electrons, phosphoryl groups, and chemical potential.

Glycolysis

Glycolysis converts one glucose molecule into two pyruvate molecules through a ten-reaction pathway in the cytosol. In its standard accounting, glycolysis consumes two ATP in an investment phase and produces four ATP in a payoff phase, giving a net gain of two ATP per glucose. It also produces two NADH per glucose.

Glycolysis illustrates several general principles: pathway steps can be near equilibrium or strongly displaced from equilibrium; ATP can be formed by substrate-level phosphorylation; oxidation of a carbon intermediate can be coupled to energy conservation; and irreversible steps are common control points.

Pyruvate has several possible fates. Under aerobic conditions in many eukaryotic cells, it can enter mitochondria and be converted to acetyl-CoA by the pyruvate dehydrogenase complex. Under conditions that require regeneration of NAD+ without mitochondrial oxidation, fermentation pathways can reduce pyruvate or a derivative. The exact fate depends on organism, tissue, oxygen availability, and metabolic state.

The Citric Acid Cycle

Acetyl-CoA enters the Citric acid cycle, where its acetyl group is oxidized and the cycle regenerates oxaloacetate. Per acetyl-CoA oxidized, the cycle classically yields three NADH, one FADH2, one GTP or ATP equivalent, and two CO2. In eukaryotes, most reactions occur in the mitochondrial matrix, while succinate dehydrogenase is associated with the inner mitochondrial membrane.

The cycle is also a biosynthetic hub. Intermediates contribute to amino-acid, heme, glucose, and fatty-acid metabolism. When intermediates are withdrawn for biosynthesis, anaplerotic reactions replenish them. This dual role makes the cycle a good example of why metabolic pathways should be understood as networks rather than isolated loops.

Oxidative Phosphorylation

NADH and FADH2 donate electrons to the mitochondrial electron-transport chain. Electron transfer through the chain is coupled to proton translocation across the inner mitochondrial membrane, generating an electrochemical proton-motive force. ATP synthase uses this stored potential to drive ATP formation from ADP and inorganic phosphate.

Molecular oxygen is the terminal electron acceptor in mitochondrial aerobic respiration and is reduced to water. The electron-transport chain and ATP synthase are coupled by the proton gradient, a principle known as chemiosmosis. Uncouplers dissipate the proton gradient and can increase oxygen consumption while reducing the efficiency of ATP production; inhibitors that block electron transfer can suppress both electron flow and ATP synthesis.

The ATP yield associated with NADH or FADH2 is not a fixed integer in all contexts. Proton pumping stoichiometry, transport costs, shuttle systems, and membrane leak can change the effective P/O ratio. University-level analysis should therefore distinguish simple textbook accounting from mechanistic bioenergetics.

Metabolic Integration and Regulation

Cells coordinate pathways through substrate availability, enzyme abundance, covalent modification, allosteric effectors, compartmentation, and signaling. In mammals, insulin generally promotes nutrient storage and anabolic processes after feeding, whereas glucagon helps coordinate hepatic responses during fasting. These hormonal patterns interact with tissue-specific enzyme expression and with signals such as ATP, AMP, citrate, acetyl-CoA, and NADH.

A change in one pathway can redistribute flux throughout the network. For example, blocking a mitochondrial reaction may alter cytosolic redox balance, lactate production, biosynthetic precursors, and signaling. This systems perspective is essential when interpreting metabolic disease or drug action.

Information Flow and Molecular Biology

DNA, RNA, and Protein Synthesis

The central dogma describes major directions of sequence-information transfer among nucleic acids and proteins. DNA can be replicated, DNA can be transcribed into RNA, and RNA can be translated into protein. Reverse transcription and RNA-dependent RNA replication are important additional routes involving nucleic acids. Sequence information is not normally transferred from protein back into nucleic acid.

Replication requires templated DNA synthesis, proofreading, and coordination of leading- and lagging-strand processes. Transcription produces RNA using a DNA template. Translation uses ribosomes, transfer RNAs, messenger RNA, and many protein factors to convert nucleotide sequence into amino-acid sequence.

Biochemistry adds a mechanistic layer to molecular biology. Polymerases select substrates through binding and catalysis; ribosomes use RNA and proteins to position reactants; aminoacyl-tRNA synthetases enforce key aspects of translation fidelity; and gene-expression factors recognize molecular surfaces and chemical modifications.

Regulation, Signaling, and Post-Translational Modification

Gene expression can be regulated at transcription, RNA processing, RNA stability, translation, and protein degradation. Protein function can also be altered rapidly by phosphorylation, acetylation, methylation, ubiquitination, proteolysis, and other covalent modifications.

Cell signaling often links receptor activation to enzyme cascades and second messengers. Kinases transfer phosphoryl groups to specific targets, phosphatases remove them, and small molecules or ions can relay information. Because signaling pathways form networks with feedback and cross-talk, the effect of a signal depends on cellular state and context.

Experimental and Quantitative Biochemistry

Measuring Molecules and Reactions

Biochemistry advances by connecting molecular models to measurable evidence. Spectrophotometry can follow concentration changes when reactants or products absorb light differently. Fluorescence methods can report binding, conformational changes, localization, or reaction progress with high sensitivity. Calorimetry can measure heat changes and, in some formats, binding thermodynamics.

Chromatography separates molecules according to properties such as size, charge, hydrophobicity, or specific affinity. Electrophoresis separates charged molecules in an electric field and is widely used for proteins and nucleic acids. Mass spectrometry identifies and quantifies molecules according to mass-to-charge behavior and fragmentation patterns, making it central to proteomics, metabolomics, and lipidomics.

Structural methods provide complementary information. X-ray crystallography can reveal atomic structures of ordered crystals, nuclear magnetic resonance can characterize molecules and dynamics in solution, and cryogenic electron microscopy can resolve many large macromolecular assemblies without requiring conventional crystals.

Designing a Biochemical Experiment

A strong experiment begins with a testable question and an operational definition of what will be measured. You should identify independent variables, dependent variables, controls, replicates, calibration procedures, and plausible confounders. For enzyme assays, you should also determine whether measurements represent initial rates, whether substrate depletion is negligible, and whether the signal is proportional to product formation.

Quantitative interpretation requires uncertainty. A parameter estimate without information about experimental variability, model assumptions, and goodness of fit is incomplete. Nonlinear regression is generally preferable to linearized plots for estimating Michaelis-Menten parameters because transformations can distort error structure.

Controls help distinguish alternative explanations. A no-enzyme control can reveal nonenzymatic background; a no-substrate control can reveal baseline signal; a known-active preparation can provide a positive control; and orthogonal methods can test whether an effect seen by one technique is reproducible by another.

From Data to Mechanism

Biochemical mechanisms are models that explain observations. A mechanism becomes stronger when multiple independent forms of evidence converge: kinetics, mutagenesis, structural biology, isotope tracing, binding studies, spectroscopy, and cellular experiments.

Correlation alone does not establish causation. If a metabolite concentration rises after a treatment, possible explanations include increased synthesis, decreased consumption, altered transport, compartmental redistribution, or measurement bias. Mechanistic reasoning asks what additional experiment would separate these possibilities.

Applications of Biochemistry

Medicine and Pharmacology

Many drugs act on biochemical targets such as receptors, enzymes, transporters, ion channels, or nucleic-acid processes. Understanding binding, kinetic selectivity, metabolism, and pathway feedback helps explain both therapeutic effects and adverse effects. Clinical biomarkers such as enzyme activities or metabolite concentrations can be informative, but their interpretation depends on sampling, tissue origin, reference intervals, and disease context.

Biotechnology and Molecular Engineering

Biochemistry underlies recombinant protein production, enzyme engineering, metabolic engineering, biosensors, diagnostics, and biomanufacturing. Directed evolution can improve enzyme properties through cycles of variation and selection, while rational design uses structural and mechanistic information to propose targeted changes.

Biotechnological optimization often requires trade-offs. Increasing catalytic rate may reduce stability; changing substrate specificity may alter regulation; maximizing product yield may impair cellular growth. Systems-level analysis helps identify these constraints.

Nutrition and Metabolic Physiology

Macronutrients enter interconnected metabolic pathways rather than isolated “carbohydrate,” “fat,” or “protein” channels. Amino acids contribute to protein synthesis and nitrogen metabolism, fatty acids can be oxidized or stored, and glucose can support ATP production, biosynthesis, or storage. Hormonal and cellular signals determine how these pathways are coordinated over time.

Biochemical knowledge can clarify nutrition, but translating pathway chemistry into dietary advice requires physiological and clinical evidence. A mechanism that is chemically plausible is not by itself proof of a health outcome.

How to Study Biochemistry Effectively

Biochemistry becomes easier when you organize information by principles rather than by isolated facts. For every pathway, identify inputs, outputs, cellular location, energy carriers, irreversible or strongly regulated steps, and links to other pathways. For every protein, connect sequence and structure to mechanism. For every graph, identify the variables, units, assumptions, and what result would falsify your interpretation.

Draw pathways from memory, but do not stop at memorization. Annotate carbon flow, electron carriers, ATP usage or production, regulatory signals, and compartment boundaries. Then perturb the system: ask what would happen if an enzyme were inhibited, a cofactor became limiting, a transporter failed, or the energy state changed.

Interactive Tasks

Quiz: Test Your Knowledge

What does an enzyme change in a chemical reaction? (The activation energy barrier) (!The equilibrium constant) (!The overall free energy change) (!The identity of the final products)

At what substrate concentration does a Michaelis Menten enzyme operate at half of Vmax? (The Michaelis constant) (!The turnover number) (!The equilibrium constant) (!The inhibition constant)

Which interaction is a major driver of membrane bilayer formation in water? (The hydrophobic effect) (!Peptide bond formation) (!DNA base pairing) (!Disulfide exchange)

What is the net ATP gain from glycolysis per glucose in standard pathway accounting? (Two ATP) (!One ATP) (!Four ATP) (!Six ATP)

Which molecule is the terminal electron acceptor in mitochondrial aerobic respiration? (Oxygen) (!Pyruvate) (!Glucose) (!Acetyl CoA)

Which protein structure level is defined directly by amino acid sequence? (Primary structure) (!Secondary structure) (!Tertiary structure) (!Quaternary structure)

Which cofactor is widely used as reducing power in biosynthetic reactions? (NADPH) (!ADP) (!AMP) (!Coenzyme A)

What does competitive inhibition do in the simplest Michaelis Menten model? (Increases apparent KM) (!Decreases Vmax) (!Eliminates substrate binding) (!Changes the equilibrium constant)

Which process converts RNA sequence information into a protein sequence? (Translation) (!Replication) (!Transcription) (!Glycolysis)

What mainly powers ATP synthase during mitochondrial oxidative phosphorylation? (A proton motive force) (!A sodium chloride crystal) (!A peptide gradient) (!A DNA concentration gradient)

Memory Game

Allostery	Regulation through ligand binding at a site that changes functional behavior elsewhere
Glycolysis	Cytosolic pathway that converts glucose into pyruvate
Chemiosmosis	Coupling of ion gradient energy to ATP formation
Proteomics	Large scale analysis of proteins in a biological system
Buffer	Solution that resists pH change within a useful range
Ribosome	Molecular machine that synthesizes polypeptides from messenger RNA

Drag and Drop

Match the correct terms.	Topic
Enzyme	Biological catalyst that accelerates a reaction
NADH	Reduced electron carrier used in energy metabolism
Phospholipid	Amphipathic molecule that is a major membrane component
Transcription	Synthesis of RNA using DNA as a template
Homeostasis	Dynamic maintenance of internal biological conditions

...

Crossword Puzzle

Glycolysis	Which pathway converts glucose to pyruvate in the cytosol?
Allostery	What form of regulation changes protein activity through a separate binding site?
Coenzyme	What organic helper molecule assists some enzymes during catalysis?
Ribosome	What molecular machine translates messenger RNA into protein?
Pyruvate	What three carbon product is formed at the end of glycolysis?
Homeostasis	What term describes dynamic maintenance of internal biological conditions?

LearningApps

Cloze Text

Biochemistry connects molecular structure with

. Noncovalent interactions help stabilize proteins and

. A buffer works best when pH is near the relevant

. Enzymes accelerate reactions by lowering the

. In Michaelis Menten kinetics the velocity approaches

at high substrate concentration. Glycolysis converts glucose into

. The citric acid cycle generates reduced electron carriers including

. Oxidative phosphorylation depends on a membrane

. DNA is transcribed into

. Translation converts nucleotide information into an amino acid

.

Open-Ended Tasks

Easy

Biochemical concept map: Create a one-page concept map that connects water, amino acids, proteins, enzymes, ATP, and metabolism with labeled relationships.
Protein structure sketch: Draw the four levels of protein structure and annotate the dominant interactions that stabilize each level.
Pathway annotation: Recreate glycolysis from a reliable source and label where ATP and NADH are consumed or produced.
Biochemistry interview: Interview a laboratory student, researcher, pharmacist, or biotechnology professional about how biochemical reasoning is used in their work and summarize three insights.

Standard

Buffer design project: Design a hypothetical buffer for an enzyme assay at a chosen pH, justify the buffer system using pKa reasoning, and discuss concentration and temperature considerations.
Enzyme kinetics investigation: Use provided or simulated initial-rate data to estimate KM and Vmax by nonlinear fitting, graph the result, and explain the assumptions of the model.
Metabolic regulation explainer: Produce a short video that explains how ATP, AMP, citrate, and hormonal signals can alter metabolic flux without treating any one signal as a complete controller.
Biochemical methods comparison: Compare chromatography, electrophoresis, mass spectrometry, and one structural method for a single research question and recommend a workflow.

Advanced

Unknown inhibitor study: Design an experiment that distinguishes competitive, uncompetitive, and mixed inhibition using initial-rate measurements across several substrate and inhibitor concentrations.
Isotope tracing proposal: Propose a stable-isotope experiment that follows carbon from a labeled nutrient into at least two metabolic products and explain what different labeling patterns would mean.
Mutation mechanism project: Choose a documented enzyme mutation, predict how it could affect folding, binding, catalysis, or regulation, and design two independent tests of your prediction.
Systems biochemistry case study: Build a mechanistic model of a metabolic perturbation that links enzyme activity, redox state, metabolite concentrations, transport, and cellular phenotype, then identify evidence that could falsify your model.

Learning Assessment

Kinetic reasoning assessment: Given a set of enzyme velocity data with and without an inhibitor, determine which kinetic model best describes the data and justify the conclusion using parameter changes and residual patterns.
Thermodynamic coupling assessment: Explain how a reaction with a positive free-energy change can proceed in a cell when coupled to ATP hydrolysis, and distinguish thermodynamic favorability from reaction rate.
Metabolic flux assessment: Predict how inhibition of a mitochondrial electron-transport component could affect NADH oxidation, oxygen consumption, ATP production, and glycolytic flux, then state the assumptions behind your prediction.
Structure function assessment: Analyze a mutation that replaces a buried hydrophobic residue with a charged residue and propose consequences for protein stability and activity together with experiments that could test them.
Information flow assessment: Compare replication, transcription, and translation in terms of template, product, directionality, molecular machinery, and fidelity mechanisms, then explain one consequence of an error in each process.
Experimental design assessment: Evaluate a proposed enzyme assay for missing controls, nonlinearity, substrate depletion, and measurement bias, then redesign it to produce interpretable kinetic data.

Evidence of Learning

Knowledge: You can explain core biochemical principles, including molecular interactions, acid-base behavior, protein structure, enzyme catalysis, energy coupling, central metabolism, nucleic-acid chemistry, and information flow.

Skills: You can interpret kinetic and thermodynamic relationships, read biochemical graphs and pathways, track carbon and electrons, evaluate experimental controls, fit simple quantitative models, and distinguish data from mechanistic inference.

Products: Strong evidence includes annotated pathway diagrams, kinetic analyses, laboratory or simulation reports, concept maps, experimental proposals, short explanatory media, and evidence-based comparisons of biochemical methods.

Transfer achievements: You can apply biochemical principles to unfamiliar mutations, inhibitors, metabolic perturbations, biotechnology problems, or molecular disease mechanisms and can propose experiments that would discriminate among alternative explanations.

OERs on the Topic

The English Wikipedia article provides a broad overview and links to many related biochemical concepts:

For a university-level open course with lectures on metabolism, carbohydrates, membranes, and related topics, you can also use MIT OpenCourseWare: General Biochemistry.