Healthy Tau vs. Abnormal Tau¶
Learning Objective¶
Compare the structure and function of normal tau protein versus hyperphosphorylated tau in Alzheimer's disease (Bloom Level 2 - Understand).
Overview¶
Tau is a small protein that normally keeps a neuron's internal transport system running. It binds to microtubules — the hollow tube-shaped "rails" that carry cargo up and down the axon — and holds them in stable parallel bundles. In Alzheimer's disease tau becomes chemically modified and lets go of the microtubules. The rails fall apart, the loose tau clumps together into neurofibrillary tangles, and the neuron slowly starves and dies.
This diagram lets you compare a healthy neuron (left) and a diseased neuron (right) side by side so you can see what goes wrong at the molecular level.
How to Use This Diagram¶
Explore Mode — Hover over any numbered marker or label to read about that structure. Compare corresponding parts across the two panels: blue microtubules to broken microtubules, green tau to orange tau, healthy vesicles to stranded vesicles.
Quiz Mode — Click "Quiz" to test your knowledge. Read the hint, then click the correct marker on the diagram. Your score is tracked and a celebration plays when you answer all eight correctly.
Comparison Table¶
| Feature | Normal Tau | Hyperphosphorylated Tau |
|---|---|---|
| Location | Bound to microtubules | Detached, floating in cytoplasm |
| Structure | Extended, flexible | Misfolded, aggregated |
| Function | Stabilizes transport | Disrupts transport |
| Effect | Neuron health | Neuron dysfunction and death |
Key Points¶
- Normal tau acts like railroad cross-ties, holding the microtubule rails together so vesicles can be transported smoothly along the axon.
- Hyperphosphorylated tau has extra phosphate groups attached that change its shape, causing it to detach from microtubules.
- Microtubules break when tau lets go, disrupting the neuron's internal transport system.
- Neurofibrillary tangles form when detached tau clumps into twisted filaments inside the cell body — a hallmark of Alzheimer's disease.
- Synapses starve because transport vesicles can no longer reach them, eventually causing the neuron to die.