Proteins Proteins are food substances that contain carbon. hydrogen, oxygen and nitrogen. Sulfur and phosphorus are present too. Every protein molecule is made up of basic units called amino acids. Meat, fish and eggs contain animal proteins while beans, nuts and seeds contain plant proteins Importance of proteins (a) Needed for growth and repair of wom-out or damaged cells (b) Used for the synthesis of enzymes and some hormones (c) Important components of antibodies which help the body to fight diseases (d) A source of energy Insufficient protein in child's diet may lead to a disease called kwashiorkor.