My Macbook Pro from around 2008 finally died. It has two 1 GB memory chips. (Specifically, two of this Samsung chip.) My question is: can I use these chips in my 2011 Mac Pro?
No, not directly.
The Mac Pro uses full-sized desktop DIMM modules, whereas the Macbook pro uses laptop-sized SO-DIMM modules. These cannot be directly swapped without a passive adapter, which I honestly wouldn't think makes much sense to bother with given how inexpensive 2 GB of RAM is these days for a Mac Pro.