Visual explainer
Cell Biology
Diffusion vs. osmosis
Two ways molecules move. One important difference.
4 min read · Go at your own paceA little curiosity goes a long way
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A closer look at lifeFIG. 01
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Visual explainer
Biochemistry
How do enzymes work?
Meet the active site, where binding meets catalysis.
5 min read · Go at your own pace
Visual explainer
Biochemistry
Inside the Krebs cycle
Follow the cycle that helps cells harvest energy.
3 min read · Go at your own pace
Visual explainer
Cell Biology
Mitosis, step by step
See how one cell divides into two daughter cells.
5 min read · Go at your own pace
Visual explainer
Cell Biology
What is a concentration gradient?
Make sense of the difference that drives diffusion.
4 min read · Go at your own pace
Visual explainer
Cell Biology
Across the cell membrane
Explore the boundary that connects a cell to its world.
8 min read · Go at your own paceFind your field
A world within every subject.
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How does oxygen get across a cell membrane? Follow a simple diffusion model, one step at a time.
- Spot the differenceMore oxygen molecules on one side than the other.
- Follow the movementNet movement goes down the concentration gradient.
- See the balanceAt equilibrium, molecules still move both ways.
Simple diffusionTry it yourself
Outside the cellInside the cell
Cell membrane Oxygen (O₂)Illustrative model · Not to scale
01 / 03
Concept reference: OpenStax Biology 2e, §5.2 A concentration gradient: 14 oxygen molecules outside, 4 inside. The two compartments have equal volume.
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One lesson leads to the next.
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Cell Biology3 connected readings
Understand cell transport
From a concentration gradient to the ways cells move materials.
Start learningBiochemistry3 connected readings
From glucose to ATP
Connect the stages that help cells release energy from glucose.
Start learningA small check. A stronger connection.
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