Nope these methods do not need pdb file. Assemblies themselves contain that information. See below from msdn.
Assemblies contain modules, modules contain types, and types contain members. Reflection provides objects that encapsulate assemblies, modules, and types. You can use reflection to dynamically create an instance of a type, bind the type to an existing object, or get the type from an existing object. You can then invoke the type's methods or access its fields and properties.
You can read this link to better understand reflection: http://msdn.microsoft.com/en-us/library/f7ykdhsy.aspx