Question

Site of bacterial respiration is
A. Microsome
B. Episome
C. Mesosome
D. Ribosome

Answer 1

Bacteria are microscopic organisms that belong to a large domain of prokaryotic microorganism. The bacterial cells are found in a variety of shapes and are found to be present in different habitats ranging from the cold to the thermal springs as well as in the acidic environment. The bacterial cell is able to perform all different cell functions and some of their cell structures are different from the eukaryotic cells.

Complete answer:
Bacteria are prokaryotic organisms that lack a well-defined nuclei and membrane bound organelles. The chromosomes are not bounded by membrane and are not complex. They contain a single closed DNA arranged in a circle lying freely in the cytoplasmic matrix. The different other components of the cell of bacteria are cell wall, cytoplasmic membrane, cytoplasm, plastids, ribosomes, pili, nucleoid and mesosomes.

The plasma membrane in the bacterial cell is an important organelle and it is composed of phospholipid bilayer. It performs several important functions such as protection, as a barrier and it also serves as a location for transport of molecules. The plasma membranes at certain points are invaginated or extended to produce extension-like structures that are known as the mesosomes.

From the above given options:

Option C: The mesosomes are extended part of the plasma membrane in the form of invaginations or lamellas. They are found in all gram-positive and the gram-negative bacteria. The mesosomes are membrane bound organelles that are produced by the plasma membrane and they lie close to the cell membrane. They are also referred to as the chondrin. They are known to play a role in the respiration and are considered as the site of respiration in the bacterial cell. They perform functions of oxidative phosphorylation and play an active part in respiration. The mesosome increases the surface area of the cell. Mesosomes are divided into three types on the basis of their structure which are lamellar, vesicular and tubular.

Option A: Microsomes are vesicle like structures that are formed from the endoplasmic reticulum in eukaryotic cells. They are not present in healthy living cells.

Option B: Episomes are the extrachromosomal genetic materials found in bacterial cells that are able to replicate genetically either autonomously or can be integrated into chromosomes.

Option D: Ribosomes in bacteria are composed of two subunits with a larger and other smaller subunit. The main function of ribosomes is related to the synthesis of protein and they receive and translate the genetic codes for production of specific proteins.

Hence, the correct answer is option (C).

Note: The bacterial cells contain several invagination and lamellar structures created by the plasma membranes. These structures are known as mesosomes and aid the bacterial cell in cellular respiration. They are the important site of respiration as they perform oxidative phosphorylation and are actively engaged in cellular respiration.