Description of protein structures with modules and domains, and protein folding. Use of sequence alignments to identify consensus structures, and sometimes the identity of newly found proteins, and also how related different species are. The importance of hydrophobic amino acids, which energetically prefer to be in the interior of proteins, in determining the folding of a protein chain into a folded structure. Larger proteins have more domains and therefore have more possible functions. The importance of proteins being able to change their conformation. An extended linear protein chain has positions for extra processes. Ubiquitin attracts the proteasome to degrade unfolded proteins or unnecessary proteins. A brief description of covalent and noncovalent bonds that stabilize the final protein structure. Description of protein synthesis using ribosomes and tRNAs.