Question

Bacteria DNA is a
A. Straight
B. Helical
C. Membrane-bound
D. Circular and free

Answer 1

Hint: Bacteria classify under the group of Monera. Bacteria are unicellular. Bacteria can be divided into archaebacteria and eubacteria. Archaebacteria have cell walls different from other bacteria. Eubacteria are also known as true bacteria.

Complete answer:
The cell structure in bacteria is typically prokaryotic. Bacterial cells have a chemically complex cell envelope. The cell envelope consists of a tightly bound three-layered structure. The outermost layer is called glycocalyx followed by the cell wall and the plasma membrane. The cell lacks a well-defined nucleus. and the chromatin material is centrally located, resembling the bacterial chromosome. The fluid matrix filling the cell is the cytoplasm. The genetic material is basically naked not enveloped by a nuclear membrane. Genomic DNA in bacteria is circular, free, and has a single chromosome.
Hence, the correct answer is (D).
Additional Information:
Cell Structure of cyanobacteria: The cell wall is four-layered and is invariably covered by a mucilaginous sheath, composed largely of mucopeptide. The protoplast is coloured and lacks membrane-bound organelles like endoplasmic reticulum, Golgi bodies, mitochondria, lysosomes, plastids and contain 70S ribosomes. A group of coiled membranes called lamellasome is found which connects the nucleoid to the cell membrane. It helps in the respiration and replication of DNA. The cell membrane lacks sterols.
The cell structure of Mycoplasma: These are unicellular, simplest free-living prokaryotes. They do not have cell walls so they are highly pleomorphic and can assume various shapes like spherical, granular, filamentous, coccoid. The cell membrane is the outermost limiting layer. It is a trilamellar unit membrane structure. The protoplasmic matrix contains ribosomes (70S type), fatty substances, and proteins.

Note:
In addition to the genomic DNA, many bacteria have small circular DNA outside the genomic DNA. These smaller DNA’s are called a plasmid. The one character of a plasmid is resistance to antibiotics.