Level 4 officials are the most experienced officials on the field and have 76 or more games under their belts at the start of the MLS season; all FIFA officials have Level 4 status. According to the 2009 MLS Referee Manual, Level 4 referees earn $875 per game, assistant referees earn $495 and fourth officials earn $285.fficials who work Major League Soccer games are paid based on experience. Referee experience is based on the number of regular-season and playoff games worked and is set in an MLS scale that is comprised of four levels.
The subunits of proteins are called amino acids. Amino acid molecules are smaller than protein molecules and are inside of the protein molecules. Amino acids are joined together by peptide bonds where the-COOH group and the-NH2 group of two consecutive amino acids bond with the loss of a water molecule.
Humans have tens of thousands of different proteins, each with a specific structure and function. Proteins are the most structurally complex molecules known. Each type of protein has a complex three-dimensional shape or conformation. All protein polymers are constructed from the same set of 20 amino acid monomers. Polymers of proteins are called polypeptides. A protein consists of one or more polypeptides folded and coiled into a specific conformation. Amino acids are the monomers from which proteins are constructed. Amino acids are organic molecules with both carboxyl and amino groups. 1  At the center of an amino acid is an asymmetric carbon atom called the alpha carbon. 2  Four components are attached to the alpha carbon: a hydrogen atom, a carboxyl group, an amino group, and a variable R group (or side chain).