129 articles
Biochemistry & the Chemistry of Life
Proteins, carbohydrates, lipids, DNA, enzymes and the chemistry happening inside living things.
Haemoglobin: How Blood Carries Oxygen
How haemoglobin loads oxygen in the lungs and releases it in tissues: haem and iron(II), four subunits, cooperative binding and the S-shaped dissociation curve, the Bohr effect, 2,3-BPG, fetal haemoglobin, CO₂ transport and sickle cell disease.
Hormones as Chemical Messengers
How hormones work chemically: the three structural classes (peptides, steroids and amino acid derivatives), why solubility decides where the receptor is, signal amplification and second messengers, feedback control, and examples from insulin to thyroxine.
How Antibiotics Work: Penicillin and Beyond
The chemistry of antibiotics: selective toxicity, the five main bacterial targets (cell walls, ribosomes, DNA copying, folate synthesis and membranes), how β-lactams like penicillin work, why antibiotics don't kill viruses, and the chemistry of resistance.
The Chemistry of mRNA Vaccines
How mRNA vaccines work at the molecular level: the mRNA and its cap, tail and modified nucleosides, why unmodified RNA triggers inflammation, the four lipids in lipid nanoparticles and how they deliver RNA, why the vaccines need cold storage, and what happens to the mRNA afterwards.
Insulin: The Protein That Controls Blood Sugar
A chemical profile of insulin: its two-chain structure and disulfide bridges, how it's made from proinsulin, how it lowers blood glucose, the history from Banting and Best to Sanger and recombinant insulin, diabetes, and modern insulin analogues.
Iron in the Body: Haemoglobin and Oxygen Transport
How the body uses about 4 grams of iron: haemoglobin and myoglobin, iron in enzymes, Fe²⁺ vs Fe³⁺ chemistry, how iron is absorbed, transported and stored, why there's no way to excrete it, iron-deficiency anaemia and iron overload.
Lock-and-Key vs Induced-Fit Models
Two models of how enzymes bind their substrates, compared side by side: Fischer's rigid lock-and-key and Koshland's flexible induced fit, the evidence for each, hexokinase as the classic example, and conformational selection.
Monosaccharides: Glucose, Fructose and Galactose
The structures and chemistry of the simple sugars: aldoses and ketoses, trioses to hexoses, glucose, fructose and galactose compared, isomers and D/L forms, ring formation, reducing properties and roles in the body.
Neurotransmitters: The Chemistry of the Brain
A list of the brain's main chemical messengers, grouped by chemical type (amino acids, monoamines, acetylcholine, peptides, gases and purines), with their structures, jobs, how drugs affect them, and how synapses turn electrical signals into chemistry.
Nucleic Acids: DNA and RNA Chemistry
The chemistry of nucleic acids: nucleotides and their three parts, the five bases, sugars, phosphodiester bonds and the sugar–phosphate backbone, 5′ and 3′ ends, why nucleic acids are acidic, and what DNA and RNA do.
The Peptide Bond: How Amino Acids Link
How amino acids join by condensation to form peptide bonds, why the peptide bond is flat and rigid, resonance, the protein backbone, N- and C-termini, naming dipeptides, hydrolysis in digestion, and how chemists make peptides.
Phospholipids and Cell Membranes
How amphipathic phospholipids self-assemble into bilayers, the fluid mosaic model, membrane proteins, cholesterol's role, fluidity and temperature, what can cross a membrane and how, and how detergents and soaps disrupt membranes.
Photosynthesis: The Chemistry
Photosynthesis as chemistry: the overall equation and its energy, where the oxygen comes from, the two stages inside the chloroplast, redox and light energy, limiting factors, and why photosynthesis matters for food, fuel and the atmosphere.
Starch vs Glycogen vs Cellulose
Three polymers of glucose with completely different jobs. Compare amylose, amylopectin, glycogen and cellulose: α and β links, branching, shape, solubility, digestibility and why the tiny structural difference matters so much.
Primary, Secondary, Tertiary and Quaternary Protein Structure
The four levels of protein structure explained: amino acid sequence, α-helices and β-sheets, the 3D fold held by hydrophobic interactions, hydrogen bonds, ionic bonds and disulfide bridges, and multi-subunit proteins like haemoglobin.
Serotonin: Structure and Roles
A chemical profile of serotonin (5-hydroxytryptamine): its indole structure, how it's made from tryptophan, why most of it is in the gut, its roles in mood, sleep, appetite and blood clotting, how SSRIs and psychedelics act on it, and its conversion to melatonin.
Vitamin C (Ascorbic Acid): Chemistry and Function
A chemical profile of vitamin C: structure and formula, why it's an acid, its antioxidant redox chemistry, its role in collagen and iron absorption, scurvy, industrial production, stability in food, and how to measure it by titration.
Vitamin D: The Sunshine Vitamin's Chemistry
How skin makes vitamin D with ultraviolet light: the photochemical ring-opening of 7-dehydrocholesterol, conversion to calcidiol and calcitriol, how the hormone controls calcium, D2 vs D3, food sources, deficiency, rickets and why latitude matters.
Vitamins: Fat-Soluble vs Water-Soluble
What vitamins are and why we need them, the chemistry behind water-soluble (B group and C) and fat-soluble (A, D, E, K) vitamins, how polarity decides storage, toxicity and cooking losses, the jobs each vitamin does, and deficiency diseases.
The Chemistry of Muscle Contraction
Muscle contraction at the molecular level: actin and myosin, the sliding filament model, the ATP-driven cross-bridge cycle, calcium, troponin and tropomyosin, rigor mortis and cramps.
Nerve Impulses: Sodium, Potassium and Membrane Potential
The electrochemistry of nerve impulses: ion gradients, the Nernst equation, resting potential, voltage-gated channels, the action potential, myelin, synapses and toxins.
How Molecules Cross Cell Membranes
The chemistry of membrane transport: why the lipid bilayer blocks ions, simple and facilitated diffusion, channels, carriers, pumps, co-transport, osmosis, and vesicles, with Fick's law.
Prions: Misfolded Proteins That Spread
How a protein can be infectious: the prion protein PrP, α-helix to β-sheet refolding, templated conversion, amyloid fibres, BSE and CJD, why prions resist sterilisation, and links to other diseases.
How We See: Retinal and a Single Double Bond
Vision begins when one photon flips one cis double bond in retinal. Follow the photochemistry, the G-protein cascade, colour vision and the vitamin A cycle.
CRISPR: The Chemistry of Gene Editing
How CRISPR–Cas9 edits DNA at the molecular level: guide RNA base pairing, the PAM, R-loops, the two nuclease domains, DNA repair, base and prime editing, and the limits.
How Drugs Are Designed: Receptors, Binding and Shape
How medicinal chemists design drugs: targets, binding forces, shape and chirality, structure–activity relationships, ADME, Lipinski's rules and famous examples.
Metabolism Practice Questions
12 advanced practice questions on glycolysis, the Krebs cycle, oxidative phosphorylation, ATP yields, Gibbs energy, fat oxidation, RQ and photosynthesis, with full worked answers.
The Calvin Cycle
How plants turn CO₂ into sugar: the three phases of the Calvin cycle (fixation by RuBisCO, reduction, regeneration of RuBP), the ATP and NADPH budget, Calvin's carbon-14 experiments, RuBisCO's oxygen problem, photorespiration, and C4 and CAM plants.
Cofactors and Coenzymes
The non-protein helpers enzymes need: metal-ion cofactors and their roles, organic coenzymes such as NAD⁺, FAD, coenzyme A and PLP, prosthetic groups vs cosubstrates, the vitamin connection, and what happens when they're missing.
DNA Replication: The Chemistry
DNA replication from a chemist's point of view: semiconservative copying, the Meselson–Stahl experiment, helicase and topoisomerase, why polymerases only build 5′→3′, the phosphodiester-forming reaction and its energy, leading and lagging strands, proofreading and PCR.