Biological Membranes A. Principal functions 1. Structural support 3. Regulation of exchange of materials with environment 4. Phospholipid - basic structure Chemical Structure of Phospholipid. Phospholipids in a Cell Membrane.
Some R groups are hydrophilic, some are lipophilic.
The primary structure of a protein is its sequence of amino acids. Pleated sheets also form part of the secondary structure. The tertiary structure of a protein defines the specific 3-dimensional structure of the protein that is critical for its functional characteristics. The tertiary structure is the precise 3-dimentional structure of the poly peptide chain. They are a structural element of the membrane.