Calcium: It is required by meristematic and differentiating cells. It is also used in the synthesis of cell wall and also needed during formation of mitotic spindle.
Magnesium: It activates enzymes of respiration, photosynthesis and are involved in DNA and RNA synthesis. Chlorophyll molecule contains magnesium in its structure. Magnesium also helps to maintain ribosome structure.
Sulphur: Amino acids like cysteine and methionine contain sulphur. They play an important role in protein folding by forming disulphide bonds. It is the main constituent of several coenzymes and vitamins.