The non-polar fatty acid tails of amphipathic phospholipids make the insoluble boundary of cells.
Explanation:
Cell membranes are bilayer of phospholipids. Phospholipids are amphipathic molecules and have a polar head and non-polar tail. The non-polar tails of two phospholipid layers are buried and make the core of the membrane while the polar heads are located towards the surrounding water.
This arrangement of phospholipids makes an insoluble covering of cell and helps the cell to maintain the interior distinct from the surroundings.
It makes sense that cell membranes are made of phospholipids because water cant mix in with lipids, so the phospholipids will be able to effectively block out any unwanted water or chemicals suspended in water outside of the cell.
<span>This organelle is the nucleolus.
The nucleolus is made of proteins, DNA, and RNA. They form around specific regions of the chromosomes called nucleolar organizing regions. These regions of the chromosomes contain some the genes needed for ribosome production.</span>
