The cytosol is the fluid area inside the cell membrane. Proteins are built there, in particular, with the ribosome near the rough endoplasmic reticulum. When they are built sequentially, the protein isn't well folded yet. This is particularly true if the folding requires interaction with the tail end of the protein, which is not synthesized yet. Multiple protein heads will likely have hydrophobic groups, and if not properly regulated, they would cluster and form aggregates.
The answer that is the closest to the description above is:
"The cytosol is a much more crowded environment than is typical for an in vitro experiment".
This is a repeating theme - an answer a lot of times - it is the hydrophobic interaction
Before two protein molecules forms their own hydrophobic cores, they could merge together so that the hydrophobic part is more deeply buried and therefore more thermodynamically favorable.
The last two answers are plain wrong. Chaperones do not digest protein, and they do not use energy to force protein to fold. Since hydrophobic interaction is the major driving force to get protein to fold, chaperones works by preventing intermolecular hydrophobic interaction, because once that is prevented, the intramolecular hydrophobic interaction will drive the folding of the protein folding by itself.
The answer is: "They prevent intermolecular interaction while the protein folds"
This is just memorizing, and I hate memorization, so I just looked it up.
In its ATP bound state, HSP70 does not bind to its substrate, while it its ADP bound state, HSP70 bound to a substrate.
The idea is that HSP70 has two states, the binding can be make transient,
At high temperature, entropy wins, the protein will denature, and potentially interact with each other to form aggregates.
The answer is "Protein are denatured, and at risk of forming intermolecular aggregates"
This is again a problem on memorization. HSP70 goes through transient cycles of substrate binding, and HSP60 forms a large cages.
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