Capsules

Muscle Contraction

Muscle shortens because two sets of protein filaments slide past one another, driven by myosin heads that repeatedly attach to actin, pivot, and let…

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The Cell Cycle

The ordered sequence a cell follows to duplicate itself, controlled by checkpoints that stop it proceeding until the previous stage is complete.…

Nitrogen Fixation

Air is nearly eighty percent nitrogen and almost nothing can use it. Breaking the bond that holds the molecule together is what makes proteins and…

Apoptosis

Cells kill themselves on instruction, following a controlled programme that dismantles them tidily. It builds bodies by removing what is not needed,…

Circadian Rhythms

Almost every organism runs an internal clock with a period of about a day, generated by a molecular feedback loop inside individual cells. It runs…

Osmosis

Water moves across a membrane from where solutes are dilute to where they are concentrated. It requires no pump and no energy input, it generates…

Meiosis

The cell division that halves the chromosome number and shuffles the genome at the same time. It is the reason sexual reproduction produces…

Sexual Selection

Darwin's second theory, proposed to explain traits that natural selection could not: peacock tails, antlers, birdsong, and every ornament that costs…

Convergent Evolution

Unrelated lineages repeatedly arrive at the same solution. Eyes, wings, flight, venom and photosynthesis have each evolved independently many times,…

Proven· Replicated

DNA Fingerprinting

DNA fingerprinting, also called DNA profiling, is a technique that identifies individuals by the unique patterns in their genetic material. Since its…

Proven· Replicated

Photosynthesis

Photosynthesis is the process by which plants, algae, and certain bacteria capture the energy of sunlight and use it to turn carbon dioxide and water…