Final answer:
Microsomal vesicles are made predominantly from fragments of the endoplasmic reticulum and the Golgi apparatus. They are isolated through cell homogenization and differential centrifugation, allowing for the study of these specific organelles in detail.
Step-by-step explanation:
The microsomal vesicles obtained by centrifugation of homogenized cells are primarily made up of fragments from the endoplasmic reticulum and the Golgi apparatus. These organelles are involved in the synthesis and packaging of proteins and lipids, which is why their remnants form the microsomes after the cell is fractionated.
During cell fractionation, cells are lysed to release their constituent parts, and then subjected to differential centrifugation. The microsomal fraction, containing vesicles that are pinched off of the original organelles, is isolated from other cellular components based on its size and density. This is an essential step in studying subcellular structures, as each fraction can then be analyzed more closely to understand the functions and interactions of various organelles.