Proteins have structural and mechanical functions. Choose...KeratinCollagenHomocysteineAlbumin, the most abundant protein in mammals, gives skin and bones their elastic strength. The proteins that turn energy into mechanical work are known as Choose...mechanicalstructuraltransfermotor proteins. These proteins are also involved in cell division and sperm swimming. Proteins that catalyze chemical reactions without being used up are Choose...antibodieshormonesneurotransmittersenzymes. Choose...AntibodiesHormonesNeurotransmittersEnzymes are chemical messengers that are made in one part of the body but act on cells in other parts of the body. Choose...AntibodiesHormonesNeutrotransmittersEnzymes are blood proteins that attack and inactivate bacteria and viruses. If the body does not have enough protein to maintain normal levels of blood proteins, fluids will leak into surrounding tissues and cause edema. Proteins help maintain Choose...hormoneacidpHhomeostatis levels in body fluids, by serving as buffers; they donate hydrogen ions when conditions are alkaline. They pick up extra hydrogen ions when conditions are acidic and donate hydrogen ions when conditions are alkaline. More than 1/3 of the energy your body uses at rest is consumed by the sodium-potassium protein pump which controls cell volume and nerve impulses. If the diet does not provide enough energy to sustain vital functions, the body will sacrifice its own protein to make energy and glucose. To release energy from an amino acid, the body performs a process called Choose...desynthesisdenaturationdeaminationtransamination.