What gets through a cell membrane, and how?
Eight live models, from molecules that slip right through, to cells that swallow whole bacteria. Press start, watch, then try the controls.
How molecules get into and out of cells · AP Biology Unit 2
Work in order, from passive transport to active transport to bulk transport to wrap-up. Click any stop to jump there.
Eight live models, from molecules that slip right through, to cells that swallow whole bacteria. Press start, watch, then try the controls.
You’ll go back to the list of labs. Your progress here, including check answers and your sort score, won’t be saved.
Tap a scenario below, then tap the kind of transport above that it shows. Your score counts first tries only.
Kinds of transport · tap one after choosing a scenario
Scenarios · tap one first
The big picture
| Type | Energy (ATP)? | Protein needed? | Direction | Examples from this lab |
|---|---|---|---|---|
| Simple diffusion | No | No | High → low | O₂ in, CO₂ out |
| Facilitated diffusion | No | Yes: channel or carrier | High → low | K⁺ channels, aquaporins, GLUT4 |
| Active transport | Yes, directly (pumps) or through an ion gradient (cotransport) | Yes: pump or transporter | Low → high | Na⁺/K⁺ pump; Na⁺–glucose cotransport (extension) |
| Bulk transport | Yes | No tunnel; the membrane itself forms vesicles | In (endocytosis) or out (exocytosis) | Insulin release, phagocytosis, pinocytosis, receptor-mediated endocytosis of LDL |