- How did von Laue's experiment simultaneously test whether X-rays were waves and whether crystals were periodic lattices?
- What did the spotted patterns on Friedrich and Knipping's photographic plates reveal about crystal structure?
- How did X-ray crystallography go on to reveal the structure of DNA and haemoglobin?
X-Ray Crystallography
Determining atomic structure from X-ray diffraction patterns.
- Why did Max von Laue expect that firing X-rays through a crystal would produce a diffraction pattern?
- How does the angle at which scattered X-ray beams emerge from a crystal reveal atomic spacing?
- What later discoveries depended on the X-ray crystallography method von Laue established?
- How did Lawrence Bragg's equation connect the angle of X-ray diffraction to the spacing between atomic planes in a crystal?
- What did William Bragg's ionisation spectrometer let the pair measure that earlier diffraction images could not show precisely?
- Why do William and Lawrence Bragg remain the only parent-child pair to share a Nobel Prize?
- What do each of the terms in Bragg's law, nλ = 2d sin(θ), represent physically?
- Why do X-rays reflected from successive crystal planes reinforce each other only at specific angles?
- How does running Bragg's law in reverse let scientists reconstruct a crystal's internal atomic geometry?
- What later scientific discoveries, from penicillin to DNA's double helix, depended on Bragg's law?
- How did Peter Debye use X-ray and electron diffraction to determine molecular architecture?
- What did Sumner crystallize in 1926, and what did it prove about the chemical nature of enzymes?
- Why did the biochemistry establishment resist Sumner's claim that enzymes were proteins for nearly a decade?
- What other proteins did Northrop and Stanley crystallize to reinforce Sumner's original claim?
- How did establishing enzymes as proteins lay groundwork for modern pharmaceutical drug design?
- What did Franklin's X-ray crystallography reveal about the position of the phosphate groups in DNA?
- What is the difference between the A-form and B-form of DNA that Franklin identified?
- What role did Rosalind Franklin's X-ray diffraction images play in Watson and Crick's model, and why has that contribution been contested?
- How did Linus Pauling combine quantum mechanics with X-ray crystallography to explain why atoms bond in the shapes they do?
- How does X-ray crystallography reveal the atomic structure of something as large and irregular as a protein?
- What insight led von Laue to propose that crystals could act as a diffraction grating for X-rays?
- What two open questions in physics did the Friedrich-Knipping experiment settle at once?
- How did von Laue's X-ray crystallography technique later contribute to determining the structure of DNA?
- How did von Laue resist the Nazi regime's campaign against Jewish scientists in Germany?
- How did Schrödinger's 1944 book What Is Life? influence Francis Crick's move into biology?
- What was the 'phase problem' in X-ray crystallography, and how did attaching heavy atoms like mercury solve it?
- What role did Rosalind Franklin's X-ray diffraction images play in Watson and Crick's model, and why has that role remained contested?
- How does X-ray crystallography work backwards from a diffraction pattern to a molecule's three-dimensional structure?
- What debate about penicillin's structure did Dorothy Hodgkin settle in 1945?
- Why did solving the structure of vitamin B12 take Hodgkin eight years and early computing assistance?
- What other major molecule did Hodgkin spend 35 years working on, from 1934 to 1969?
- How long did Dorothy Hodgkin work on determining insulin's structure, and what other structures did she solve along the way?
- What resolution did Hodgkin's 1969 insulin structure achieve, and why did that matter?
- How did X-ray crystallography help Lipscomb map the structure of borane compounds?
- Why did X-ray crystallography fail for molecules that would not form crystals, and why did electron microscopy flatten the structures it imaged?
- How did Aaron Klug combine multiple two-dimensional electron microscope projections into a three-dimensional structure?
- What is the phase problem in X-ray crystallography and why did it stall structure determination?
- How did Hauptman and Karle use statistical analysis of intensities to recover phase information?
- How did earlier crystallographers work around the phase problem before direct methods existed?
- What impact did direct methods have on the speed of drug structure determination?
- Why did membrane proteins resist crystallization for so long, and how did Michel's detergents solve the problem?
- What did the atomic-resolution structure of the photosynthetic reaction centre actually show about how a photon becomes chemical energy?
- Why was this structure considered the most complex ever determined at the time?
- What did Roderick MacKinnon's crystallised potassium channel structure reveal that electrical measurements alone could not?
- How did Kornberg's crystallography reveal the structure of the transcription machinery?
- How did crystallising the ribosome at atomic resolution reveal where antibiotics attach to it?
- What did Kobilka's crystal structure of the beta-2 adrenergic receptor reveal about how it gets activated?
- Why was crystallising a receptor in the act of activation considered so difficult?
- How did Akasaki and Amano's crystal-growing method on sapphire substrates solve the gallium nitride problem?
- Why did many proteins, especially membrane proteins, resist the older method of crystallisation for imaging?
- What accuracy did DeepMind's AlphaFold2 achieve at CASP14, and how did it compare to X-ray crystallography?