You will be given a definition of a task first, then some input of the task.
In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.

It is a double lipid bilayer membrane which surrounds the chromosomes and nucleolus in eukaryotic cells .
Output:
The nuclear envelope , also known as the nuclear membrane , is made up of two lipid bilayer membranes which in eukaryotic cells surrounds the nucleus , which encases the genetic material .