The percentage of a cell that is protein varies depending on the type of cell and its function. However, proteins generally make up a significant portion of a cell's dry weight.

Here's a breakdown:

* Average: Proteins typically constitute around 10-20% of a cell's total weight, but this can fluctuate significantly.

* Muscle cells: Muscle cells are rich in protein, with up to 80% of their dry weight composed of protein.

* Bacteria: Bacteria have a relatively high protein content, often around 50-60% of their dry weight.

* Other cell types: Other cell types, like red blood cells, have lower protein percentages, with around 30% of their dry weight being protein.

It's important to remember that water makes up the majority of a cell's total weight. So, while proteins are a significant component, their percentage of total cell weight is lower than their percentage of dry weight.