Eosinophils, like all white blood cells, are part of the immune system. They are responsible for combating multicellular parasites and certain infections. Along with mast cells, they also control mechanisms associated with allergy and asthma.

CREDIT: KATERYNA KON

This molecule transports oxygen around the body in red blood cells. It consists of four globin proteins (amino acid chains; blue stick model). Each globin protein is wrapped around a haem group (red stick model).

CREDIT: JUAN GAERTNER

Computer model of the secondary structure of an immunoglobulin antibody molecule.

This is the most abundant immunoglobulin and is found in all body fluids. Each Y-shaped molecule has two arms (top) that can bind to specific antigens, for instance, bacterial or viral proteins. In doing this they mark the antigen for destruction by phagocytes, white blood cells that ingest and destroy foreign bodies. Antibodies can also kill some pathogens directly and can neutralise toxins.

The background shows proteomic symbols, including part of a DNA molecule and protein gel spots. Proteomics is the study of the structure and function of all of the proteins in an organism.

CREDIT: ALFRED PASIEKA