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(a) Golgi Apparatus: Golgi apparatus first described by Camillo Golgi. There are three distinct components are visible in the Golgi complex. They are

• Flattened sacs or cisternae

• Clusters of tubules and vesicles, and

• Large vesicles or vacuoles

Golgi apparatus has a convex forming face and a concave maturing face. The forming face receives vesicles from ER and maturing face produces secretory vesicles and lysosomes.

Golgi apparatus absent in bacteria, blue green algae, mature sperms and RBC of mammals and other animals.

Function: (i) The main function of Golgi apparatus is secretory. It helps in the secretion of mucus, enzymes and hormones.

(ii) It helps in the storage of secretory products.

(iii) Golgi apparatus is also involved in the synthesis of cell wall, plasma membrane and lysosomes.

(b) Mitochondria: Mitochondria are tiny bodies of varying shapes and size, found in the cytoplasm. Each mitochondrion is covered by a double-membrane envelope. Outer membrane is smooth and porous while inner membrane is projected with finger-like structures, the cristae. These cristae create a large surface area for ATP-generating chemical reactions. The cristae as well as inner membrane possess small tent like particles called F1 particles or oxysomes.

The cavity of mitochondria is filled with matrix. The mitochondrial matrix contains lipids, proteins, circular DNA and RNA.

Functions of mitochondria:

(i) Mitochondria is the site of cellular respiration or oxidation of food in a cell.

(ii) The energy, released in the form of ATP, is used by body cells to synthesise new chemical compounds and to carry out other metabolic activities.