Question

The metachromatic granules are
A. Present in plant cell at metaphase stage
B. Inclusion bodies in bacteria
C. Produced in insects during metamorphosis
D. Chromatophores in animal skin

Answer 1

Hint: Metachromatic granules are normally located in the prokaryotic cell. They are made of complex polyphosphate, lipid and nucleoprotein (volutin) molecules. In certain cells, polyphosphates act as an energy reservoir and can function as an energy source for reactions.

Complete Answer:
Prokaryotes are unicellular species whose organelles or other internal membrane-bound structures are absent. Therefore, they do not have a nucleus, but only usually have a single chromosome: a fragment of circular, double-stranded DNA found in a cell region called the nucleoid.

Numerous bodies or granules are found in the bacterial cytoplasm. These bodies do not have a membrane cover and act as storage vessels. For instance, Glycogen, which is a glucose polymer, is stored as a reserve for carbohydrate and energy. Volutin, or metachromatic granules, consists of polymerized phosphate and acts as storage type for inorganic phosphate and energy.

Metachromatic granules consist of polymetaphosphate and are common in diphtheria bacillus and some lactic acid bacteria. These granules are refractive and thus readily visible under a light microscope. They have a metachromatic effect i.e., they appear red or a different hue of blue when stained with methylene blue or toluidine blue.

Thus, the correct answer is option B i.e., Inclusion bodies in bacteria.

Note: Polyphosphates serve as intracellular phosphate reserve when nucleic acid synthesis does not occur, and when synthesis of nucleic acids begin later, they are degraded and used as a source of nucleic acid phosphate.