RCSB Protein Data Bank

Bismillahirrahmanirrahim..

I am now in class. Computer in Sciece class.  As usual, we are having this so-called on the spot assigment.

Here, I present to you..

Source
Polymer: 1 Scientific Name: Escherichia coli Expression System: Escherichia coli   Polymer: 2 Scientific Name: Synthetic construct 

Source
Polymer: 1 Scientific Name: Thermotoga maritima Expression System: Escherichia coli

Source
Polymer: 1 Scientific Name: Escherichia coli Expression System: Escherichia coli

Source
Polymer: 1 Scientific Name: Escherichia coli k-12 Expression System: Escherichia coli   Polymer: 2 Scientific Name: Synthetic construct 

Source
Polymer: 1 Scientific Name: Escherichia coli k-12 Expression System: Escherichia coli   Polymer: 2
Scientific Name: Synthetic construct

anyone can explain to me all these?

reference:http://www.pdb.org/pdb/home/home.do

Best regards,