From a drop of pond water to a single atom

Four ways in

Explore each level up close

• Microorganisms

  Organisms

  Single-celled life under a virtual microscope.

  Open the microscope
• Cells and cell parts

  Cells

  Look inside different kinds of cells.

  Browse cellsMuscle cell: zoom from a muscle down to one molecule
• Big molecules and molecules

  Molecules

  Molecules you can turn and zoom, atom by atom.

  Browse molecules
• Atoms

  Periodic table

  All 118 elements, each with a short description.

  Open the periodic table
• Atoms into molecules

  Molecule lab

  Build molecules atom by atom, with the bonding rules explained.

  Open the lab
• Cells at work

  How life works

  Step-by-step animations of DNA to protein, cell division, respiration, photosynthesis and osmosis.

  See how it works

Physics of life

• Light and leaves

  Follow a photon

  Ride one bit of sunlight through a prism and into a leaf.

  Follow it
• Size and water

  Shrink yourself

  Shrink from swimmer size to a bacterium and feel water turn thick.

  Shrink down
• Temperature and bonds

  Heat vs bonds

  Turn up the heat and watch DNA melt, an egg protein unfold and ice turn to steam.

  Turn it up

Your body

• Nerves

  Neuron spark

  Fire a model neuron and watch ions rush through their channels.

  Fire it
• Food and body

  Vitamins and minerals

  What 25 vitamins and minerals do in your body, and what happens without them.

  Open the list
• Blood

  Hemoglobin breathing

  Watch the real hemoglobin molecule change shape as it picks up oxygen.

  Watch it breathe

Molecules up close

• Size

  Size lineup

  All 40 molecules side by side at true scale, from water to a virus shell.

  See the lineup

Where the sizes on the ruler come from

The ruler and the sizes things are drawn at follow these sources. The shapes are drawn by code, so treat them as illustrations; only the ATP and its atoms use real measured positions.