Assuming that you are looking for supporting evidence, so here are two of them:
1. Both mitochondria and chloroplasts (said to have become organelles through endosymbiosis) have their own DNA different from the cell's nucleus.
<span>2. During a cell's division, mitochondria and chloroplasts divide independently by binary fission.</span>
Cells are surrounded by a plasma membrane<span>. The </span>membrane<span> is composed of a phospholipid bilayer arranged back-to-back. It'</span><span>s also covered with cholesterol molecules and proteins. The </span>plasma membrane picks what goes in and out of the cell
The answer to your question would be Titin. Hope this helps:)
Rough ER<span> looks like sheets or disks of bumpy membranes while </span>smooth ER<span> looks more like tubes. </span>Rough ER<span> is called </span>rough<span> because it has ribosomes attached to its surface. The double membranes of </span>smooth<span> and </span>rough ER<span> form sacs called cisternae.</span>