ANATOMY

Detailed explanation-1: -organelle envelope A double membrane structure enclosing an organelle, including two lipid bilayers and the region between them. In some cases, an organelle envelope may have more than two membranes.

Detailed explanation-2: -Mitochondria are oval-shaped, double-membrane organelles (Figure 3.17) that have their own ribosomes and DNA. Each membrane is a phospholipid bilayer embedded with proteins. The inner layer has folds called cristae, which increase the surface area of the inner membrane.

Detailed explanation-3: -Which of the following describes the structure and function of the cell membrane? The hydrophilic head groups of the lipid molecules are exposed to the outside of the cell and the cytoplasm, which is a water-like environment. The hydrophobic tails form an oily layer inside the membrane that keeps water out of the cell.

Detailed explanation-4: -Besides the nucleus, two other organelles-the mitochondrion and the chloroplast-play an especially important role in eukaryotic cells. These specialized structures are enclosed by double membranes, and they are believed to have originated back when all living things on Earth were single-celled organisms.