what are phospholipids made of
Phospholipids consist of a polar molecule, a phosphate group, a glycerol unit and two fatty acids. They are found in cell membranes, which enclose the cytoplasm and other parts of a cell. Steroids include cholesterol, cortisone and sex hormones, such as estrogen, testosterone and progesterone. They have a carbon backbone that contains four fused ring-like structures.