Question

How many basal body rings are present in gram(+)ve bacterial cells
A. 3
B. 2
C. 4
D. 5

Answer 1

Hint: Basal body is also known as basal granule. The basal body is embedded outside the cytoplasm under the plasma. The Basal body attaches flagella to the cell wall and plasma membrane. It consists of a small central rod that is inserted into a row of rings.

Complete answer:
Basically, cilia or flagella can attach to particles embedded in the pure cytoplasmic layer just below the plasma membrane called the basal body.
Gram-negative bacteria -Gram-negative bacteria, two pairs of rings, the proximal ring and the distal ring, are connected by a central rod. There are two pairs of rings viz. The four rings are an L ring (lipopolysaccharide), a P ring (peptidoglycan), an S ring (super membrane), and an M ring (membrane).
The outer pair of ring, It means L-ring and P-ring are attached to the peptidoglycan and polysaccharide layers of the cell wall and the inner pair of ring It means S-ring and M-ring are attached to the cell membrane.
The outer ring forms a bearing through which the rod can pass.
Gram-positive bacteria-In Gram-positive bacteria, there is only a pair of rings distally (inside). The S-ring is attached to the inner thick layer of peptidoglycan, and the M-ring is attached to the cell membrane.
In Gram positive bacteria which do not have an outer lipopolysaccharide layer, there are only S and M rings. There is a pair of proteins called Mot A and Mot B that surround the inner ring and bind to the plasma membrane. Apart from the Mot protein, there is another set of proteins called Fli proteins (Fli G, Fli M, and FliN).

So the correct option is (B).

Note:
M. L. De Pamphilis and J. Alder (1971) isolated the basal flagella from the bacteria E. coli and B. subtilis and investigated the microstructure and position of the ring.
At the end of the cell cycle, the basal body controls the primary cilia and is located in the cell cortex near the plasma membrane. When they enter the cell cycle, the cilia are reabsorbed and the basal body migrates to the nucleus, which controls the centrosome. The centrioles, basal body, and cilia are important for mitosis, polarity, cell division, protein exchange, signalling, motility, and sensory function.