Four Payoffs, One Wall

You'll learnwhy a cell partitions itself into membrane-wrapped rooms instead of mixing all its chemistry.

A eukaryotic cell is barely open space — it is partitioned into membrane-wrapped rooms, and the exam question is never “name them.” It is why bother? Watch a compartment run acid chemistry next door to neutral, store energy in a proton difference, and keep a poison in the room that makes it. Twelve short steps; press Next for each one.

AP BIOLOGY · 12 STEPS · 6 QUICK CHECKS · LYSOSOME pH ≈ 5 · CYTOSOL pH ≈ 7.2 · H⁺ PUMPED OUT OF THE MATRIX · v5

acid next door to neutral · a held difference · walls do chemistry

Before you start

What you're looking at

One eukaryotic cell with its organelles appearing one at a time — nucleus, mitochondrion, lysosome, peroxisome, ER and Golgi — around a labeled cytosol.

The question

Why build inner walls instead of letting every reaction share one space?

Step 1 / 12