Question

Secondary lysosomes are also called as
A. Autophagic vacuoles
B. Lipofuscin granules
C. Residual body
D. Heterophagosomes

Answer 1

Hint: The main digestive compartment of cells is known as Lysosomes. They contain a variety of enzymes which are capable of degrading various types of biological material including lipids, proteins and nucleic acids. Depending upon their function and morphology four types of lysosomes are present— primary, secondary, auto-phagic vacuoles and residual bodies.

Complete answer:
Lysosomes contain hydrolytic enzymes in the form of semi crystalline or minute crystalline granules of size 5-8 nm. These are small vesicles that are bounded by a single membrane. Except for red blood corpuscles, lysosomes occur in all animal cells. In fungi and plants, their function is taken over by the vacuoles. In animals, lysosomes are abundant in macrophages, leucocytes, Kupffer’s cells and similar types of cells with phagocytic activity.

Secondary lysosomes are also known as heterophagosome. They are formed as a result of the fusion of food containing phagosomes with lysosomes (having digestive or hydrolytic enzymes). The digested food particles pass out into the cytoplasm. Finally, undigested food is left in the secondary lysosome. Secondary lysosomes can release their enzymes into the cell cytoplasm for exocytosis. Exocytosis is where enzymes are released outside the cell or in to the cytoplasm or where they degrade different types of material. Secondary lysosomes are larger in size compared to primary lysosomes,

Hence, the correct answer is option (D).

Note: Primary lysosomes are newly pinched off vesicles from the Golgi apparatus, and to become fully functional, they generally fuse with some endosomes. The primary lysosomes have small size and contain hydrolytic enzymes in the form of granules. Tertiary Lysosomes or residual bodies are in which only indigestible food materials have been left. Autophagic vacuoles are produced by fusion of a number of primary lysosomes around the worn out or degenerate intracellular organelles.