Question

In healthy areas: The transport system is organized in orderly parallel strands somewhat like railroad tracks. Food molecules, cell parts and other key materials travel along the "tracks."

A protein called tau (rhymes with wow) helps the tracks stay straight.
In areas where tangles are forming:
A Tau collapses into twisted strands called tangles.
B The tracks can no longer stay straight. They fall apart and disintegrate.
C Nutrients and other essential supplies can no longer move through the cells, which eventually die.
D None of these

Answer 1

The student's question revolves around the pathological role of tau proteins in Alzheimer's Disease. Normal tau proteins stabilize neuron transport tracks, while misshapen tau proteins lead to neurofibrillary tangles, disrupting transport and causing neuron death.

Step-by-step explanation:

Neurons in healthy areas of the brain have an organized transport system with parallel strands akin to railroad tracks, where proteins like tau help maintain their straight structure, ensuring that nutrients and other materials travel efficiently. In the context of Alzheimer's Disease, the tau protein can become misshapen, leading to neurofibrillary tau protein tangles. This malformation results in the disruption of the transport system, and ultimately, neuronal death. The process is compared to a collapse of the tracks, where the dysfunctional tau proteins fail to support the microtubules, instigating their disintegration and hindering the delivery of essential supplies within the cell.

Consequently, affected neurons lose function, disconnect from other neurons and die, a hallmark seen in severe cases of Alzheimer's Disease revealing brain shrinkage compared to healthy brains. Diseases characterized by misfolded proteins that accumulate and potentially become toxic, like in Alzheimer's, are known as proteopathies. Disorders such as Creutzfeld-Jacob disease and cystic fibrosis are also included in this category.